Controlling light penetration for stereolithographic manufacturing of dense objects

ABSTRACT

Systems, methods, components, and materials are disclosed for stereolithographic fabrication of three-dimensional objects. A resin including particles dispersed in a binder system can be substantially transparent to light of a wavelength sufficient to cure at least one component of the binder system. A green object can be formed by activation light penetrating into each layer of a plurality of layers of the resin in a layer-by-layer process to crosslink, polymerize, or both, at least one component of the binder system in successive layers of the resin to one another. Through subsequent processing, the green object can be densified to form a metal object, a ceramic object, or a combination thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(e) of U.S.Prov. App. No. 62/421,716, filed Nov. 14, 2016, and U.S. Prov. App. No.62/474,014, filed Mar. 20, 2017, with the entire contents of each ofthese applications hereby incorporated herein by reference.

BACKGROUND

Stereolithography is an additive manufacturing technique for fabricatinga three-dimensional object. Systems using this technique control theincidence of a light source on a liquid polymer to cause controlled,local hardening of the polymer and, ultimately, to build thethree-dimensional object layer-by-layer. The result is athree-dimensional object made of one or more polymers and, thus, subjectto the physical limitations of those constituent polymers.

SUMMARY

Systems, methods, components, and materials are disclosed forstereolithographic fabrication of three-dimensional objects. A resinincluding particles dispersed in a binder system can be substantiallytransparent to light of a wavelength sufficient to cure at least onecomponent of the binder system. A green object can be formed byactivation light penetrating into each layer of a plurality of layers ofthe resin in a layer-by-layer process to crosslink, polymerize, or both,at least one component of the binder system in successive layers of theresin to one another. Through subsequent processing, the green objectcan be densified to form a metal object, a ceramic object, or acombination thereof.

According to one aspect, a resin can include a first binder, a secondbinder different from the first binder and in a mixture with the firstbinder, and particles (e.g., metal, ceramic, or a combination thereof)suspended in the mixture of the first binder and the second binder. Theparticles can be thermally processable to coalesce with one another intoa mass, at least one of the first binder and the second binder can bereactive to crosslink or polymerize upon sufficient exposure of thefirst binder and the second binder to a predetermined wavelength oflight, and the first binder and the second binder can be separatelyextractable from the mass following crosslinking or polymerization ofthe at least one of the first binder and the second binder.

In some implementations, the particles can be sinterable to coalescewith one another into the mass. Further or instead, the particles can beinfiltratable with a liquid metal to coalesce with one another into themass.

In certain implementations, the first binder can be substantiallynon-reactive under exposure to the predetermined wavelength of lightsufficient to cross-link or polymerize the second binder.

In some implementations, the first binder can include a wax extractablefrom the second binder by chemical solvation in a non-polar chemicalfollowing sufficient exposure of the first binder and the second binderto the predetermined wavelength of light to crosslink or polymerize thesecond binder.

In certain implementations, the first binder can include a plurality oflow-molecular weight constituents, each constituent extractable from thesecond binder by a chemical solution following sufficient exposure ofthe first binder and the second binder to the predetermined wavelengthof light sufficient to crosslink or polymerize the second binder.

In some implementations, the resin can be a non-Newtonian fluid at 25°C.

In certain implementations, exposure to light at a wavelength of about300 nm to about 450 nm is sufficient to crosslink or polymerize at leastone of the first binder and the second binder.

In some implementations, the resin can further include one or more of aphoto-absorber or a photo-initiator suspended in the mixture includingthe first binder and the second binder.

In certain implementations, a concentration by volume of the particlesin the resin is within ±25 percent of a tap density of the particles.

In some implementations, the first binder can include one or more of thefollowing: paraffin wax, carnauba wax, stearic acid, polyethyleneglycol, polyoxymethylene, oleic acid, and dibutyl phthalate. Further orinstead, the second binder can include one or more of the following:poly(methyl methacrylate), polyethylene glycol diacrylate, urethaneoligomers functionalized to acrylate groups, epoxy oligomersfunctionalized to acrylate groups, 1,6-Hexanediol acrylates, or styrene.

According to another aspect a method of additive manufacturing of athree-dimensional object can include providing a layer of a resin on amedia source, the resin including particles suspended in a mixture of afirst binder and a second binder, directing light energy onto each layerof a plurality of layers of the resin to crosslink or polymerize atleast one of the first binder and the second binder of the resin on asubstrate carried by a build plate, the light energy directed onto theresin in a respective predetermined pattern associated with each layerto form a three-dimensional object, thermally processing the particlesin the three-dimensional object to coalesce the particles to oneanother, extracting the first binder from the three-dimensional objectin a primary debinding process, and extracting the second binder fromthe three-dimensional object in a secondary debinding process differentfrom the primary debinding process.

In certain implementations, thermally processing the particles in thethree-dimensional object can include sintering the three-dimensionalobject. Additionally, or alternatively, thermally processing theparticles in the three-dimensional object can include infiltrating thethree-dimensional object with a liquid metal. Further, or instead,thermally processing the particles in the three-dimensional object caninclude thermally-activating pyrolysis of at least one of the firstbinder and the second binder into a ceramic.

In some implementations, one or both of the primary debinding processand the secondary debinding process can include thermal debinding,chemical debinding, or a combination thereof.

In certain implementations, directing light energy onto each layer ofthe plurality of layers of the resin can include crosslinking orpolymerizing the first binder and the second binder, and the primarydebinding process includes breaking down the crosslinked or polymerizedfirst binder. For example, the first binder can include acrylicanhydride, methacrylic anhydride, or a combination thereof.

According to another aspect, a method of additive manufacturing caninclude providing a layer of a resin on a media source disposed within aworking volume defined by a build chamber, curing discrete portions ofthe layer of the resin on a substrate carried on a surface of a buildplate in the working volume, separating the cured discrete portions ofthe layer from the media source, wherein the separation of at least oneof the cured discrete portions is independent of the separation of atleast another one of the cured discrete portions, and, for a pluralityof layers, repeating the steps of providing each respective layer of theresin, curing discrete portions of each respective layer of the resin,and separating the cured discrete portions of each respective layer ofthe resin to form a three-dimensional object.

In certain implementations, the resin can include particles suspended inat least one binder, and curing discrete portions of each respectivelayer of the resin can include crosslinking or polymerizing the at leastone binder.

In some implementations, curing the discrete portions of each respectivelayer can include, along each discrete portion of the respective layerof the resin, directing light energy into the working volume through atransparent portion of the media source, the light energy sufficient tocure at least one component of the resin. For example, separating thecured discrete portions of each respective layer of the resin from themedia source can include moving one or both of the build plate and thetransparent portion of the media source relative to one another. Asanother or additional example, separating the cured discrete portions ofeach respective layer of the resin from the media source can includesubstantially continuously moving of one or both of the build plate andthe transparent portion of the media source relative to one another.Further or instead, curing the discrete portions of each respectivelayer of the resin can include substantially continuously curingadjacent discrete portions of the respective layer of the resin.

In certain implementations, separating the cured discrete portions ofeach respective layer of the resin from the media source can includemoving one or both of the build plate and the transparent portion of themedia source in a direction having a component parallel to the layer ofthe resin. Further or instead, each discrete segment of each respectivelayer of the resin spans a dimension of the surface of the build plate.Continuing with this example, separating the cured discrete portions ofeach respective layer of the resin from the media source can includemoving the transparent portion of the media source in a directiontransverse to the spanned dimension of the surface build plate.

In some implementations, at least one cured discrete portion of eachrespective layer of the resin can be separated from the media sourcebefore curing at least another discrete portion of the respective layer.For example, at least one cured discrete portion of each respectivelayer of the resin can be separated from the media before curing anadjacent discrete portion of the respective layer of the resin.

According to still another aspect, a stereolithography system caninclude a build chamber defining a working volume, a build platedisposed within the working volume, the build plate having a surface, anactivation light source, and a media source disposed within the workingvolume, the media source including a transparent portion, the activationlight source positioned to direct activation light, through thetransparent portion of the media source, to the surface of the buildplate, and one or both of the build plate and the transparent portion ofthe media source movable relative to one another to change a position ofthe transparent portion of the media source by an incrementsubstantially equal to a width of the transparent portion of the mediasource in a direction parallel to the surface of the build plate.

In certain implementations, the width of the transparent portion of themedia source can be less than a dimension of the surface of the buildplate in a direction of the changed position of the transparent portionof the media source.

In some implementations, the transparent portion of the media source canbe movable relative to the build plate along the direction parallel tothe surface of the build plate.

In certain implementations, the build plate can be movable relative tothe transparent portion of the media source along the direction parallelto the surface of the build plate.

In certain implementations, the media source can further include adispersion section, a collection section, and a reservoir in fluidcommunication with the dispersion section and the collection section,the dispersion section along a first side of the transparent portion ofthe media source, the collection section along a second side, differentfrom the first side, of the transparent portion of the media source, andthe dispersion section and the collection section. The media source canfurther include a blade movable to spread resin from the dispersionsection across the transparent portion of the media source.

In some implementations, the transparent portion of the media source canspan a dimension of the surface of the build plate. At least one of thebuild plate and the transparent portion of the media source can bemovable, for example, in a direction transverse to the spanned dimensionof the surface of the build plate.

In certain implementations, the activation light source can be a lightsource having a wavelength of about 300 nm to about 350 nm.

According to yet another aspect, a resin can include particles of afirst material, particles of a second material, the second materialdifferent from the first material, and a binder system in which theparticles of the first material and the particles of the second materialare suspended, the particles of the first material substantiallytransparent to light of a wavelength sufficient to crosslink,polymerize, or both, at least one component of the binder system.

In certain implementations, the particles of the first material and theparticles of the second material can be substantially homogeneouslysuspended in the binder system.

In some implementations, the particles of the second material can besubstantially opaque to light of the wavelength sufficient to crosslink,polymerize, or both, the at least one component of the binder system.

In certain implementations, the particles of the second material canhave an average size less than the wavelength of the light sufficient tocrosslink, polymerize, or both, the at least one component of the bindersystem.

In some implementations, the particles of the first material can includea ceramic. Further or instead, the particles of the second material caninclude a metal.

In certain implementations, the first material can be chemicallyconvertible to the second material. For example, the first material canbe chemically convertible to the second material via thermally-activateddecomposition or reduction.

In some implementations, the first material can be a metal oxidereduceable to form a metal.

In certain implementations, first material can include a ceramic, anintermetallic, or both, and the particles of the first material arechemically convertible to a first metal, and the particles of a secondmaterial include a second metal alloyable with the first metal. Theparticles of the first material can be in a relative concentration tothe particles of the second material such that an alloy of the firstmetal and the second metal meets a predetermined material standard.Further or instead, an oxide of the first metal can be less chemicallystable than an oxide of the second metal.

In some implementations, the binder system can include a first binderand a second binder, the first binder different from the second binderand in a mixture with the first binder, and the first bindersubstantially non-reactive under exposure to the wavelength of lightsufficient to crosslink or polymerize the second binder.

In certain implementations, the first binder can be extractable from thesecond binder following exposure of the second binder to the wavelengthof light sufficient to crosslink or polymerize the second binder.

According to yet another aspect, a method of additive manufacturing ofthe three-dimensional object can include providing a layer of a resin ona media source, the resin including particles of a first material,particles of a second material, the second material different from thefirst material, and a binder system in which the particles of the firstmaterial and the particles of the second material are suspended,directing light energy in a predetermined pattern onto the layer to curethe resin on a substrate carried by a build plate, the particles of thefirst material substantially transparent to the light energy, and thelight energy crosslinking, polymerizing, or both, at least one componentof the binder system, and for each layer of a plurality of layers,repeating the steps of providing each respective layer of the resin, anddirecting light energy in a predetermined pattern onto each respectivelayer of the resin to form a three-dimensional object.

In certain implementations, the light energy directed onto each layercan penetrate the respective layer to bond successive layers of theplurality of layers of the three-dimensional object.

In some implementations, the method can further include sintering thethree-dimensional object, the sintering transforming the particles ofthe first material to a metal or an additive in a metallic alloy.

In certain implementations, the method can further include removing thebinder system from the three-dimensional object through a plurality ofdebinding processes.

In some implementations, the method can further include infiltrating thethree-dimensional object with a liquid metal. For example, infiltratingthe three-dimensional object with the liquid metal can include replacingthe binder system with the liquid metal.

Other aspects, features, and advantages will be apparent from thedescription and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a stereolithography system.

FIG. 2 is a flow chart of an exemplary method of fabricating athree-dimensional object through stereolithography.

FIG. 3 shows an additive manufacturing system for use with thestereolithography system of FIG. 1.

FIG. 4 is a close-up view of a build plate of a stereolithographysystem.

FIG. 5 is a schematic representation of a stereolithography system.

FIG. 6 is a schematic representation of a stereolithography system.

FIG. 7A is a schematic representation of a fabrication system of astereolithography system.

FIG. 7B is an exploded view of a portion of the fabrication system ofFIG. 7A.

FIG. 8 is an exploded view of a portion of a media source of afabrication system.

FIG. 9 is a flow chart of an exemplary method of fabricating athree-dimensional object through stereolithography.

FIG. 10 is a flow chart of an exemplary method of fabricating athree-dimensional object through stereolithography.

FIG. 11 is a schematic representation of a fabrication system of astereolithography system.

FIG. 12 is a flow chart of an exemplary method of fabricating athree-dimensional object through stereolithography.

FIG. 13 is a schematic representation of a cross-section of a resinincluding particles of a first material, particles of a second material,and a binder system.

FIG. 14 is a flow chart of an exemplary method of additive manufacturingof a three-dimensional object using a resin including particlessubstantially transparent to light energy.

FIG. 15 is a flow chart of an exemplary method of additive manufacturingof a three-dimensional object by forming an alloy from particlessuspended in a resin.

FIG. 16 is a flow chart of an exemplary method of additive manufacturingof a three-dimensional object using a resin including a siliconepolymer.

FIG. 17 is a schematic representation of a cross-section of a metalparticle coated with a material.

Like reference symbols in the various drawings indicate like elements.

DESCRIPTION

Embodiments will now be described with reference to the accompanyingfigures. The foregoing may, however, be embodied in many different formsand should not be construed as limited to the implementations set forthherein.

All documents mentioned herein are hereby incorporated by reference intheir entirety. References to items in the singular should be understoodto include items in the plural, and vice versa, unless explicitly statedotherwise or clear from the text. Grammatical conjunctions are intendedto express any and all disjunctive and conjunctive combinations ofconjoined clauses, sentences, words, and the like, unless otherwisestated or clear from the context. Thus, the term “or” and the term “and”should each generally be understood to mean “and/or.”.

As used herein, the term “substrate” should be generally understood tobe a surface upon which a layer is formed. Accordingly, the termsubstrate should be understood to include a surface of a build plate, acoating on a surface of a build plate, a previously formed layer of athree-dimensional object being formed, and combinations thereof, unlessotherwise specified or made clear from the context.

As used herein, the term “binder system” should be generally understoodto include a plurality of binders, and is used interchangeably with therecitation of the plurality of binders. Thus, for example, a firstbinder and a second binder in a resin should be understood to be abinder system of the resin, unless otherwise specified or made clearfrom the context.

As used herein, the term “mixture” should be generally understood toinclude an aggregate of two or more substances that are not chemicallyunited and, thus, should be understood to include a solution of two ormore substances.

Recitation of ranges of values herein are not intended to be limiting,referring instead individually to any and all values falling within therange, unless otherwise indicated herein, and each separate value withinsuch a range is incorporated into the specification as if it wereindividually recited herein. The words “about,” “approximately,” or thelike, when accompanying a numerical value, are to be construed asindicating a deviation as would be appreciated by one of ordinary skillin the art to operate satisfactorily for an intended purpose. Ranges ofvalues and/or numeric values are provided herein as examples only, anddo not constitute a limitation on the scope of the describedembodiments. The use of any and all examples, or exemplary language(“e.g.,” “such as,” or the like) provided herein, is intended merely tobetter describe the embodiments and does not pose a limitation on thescope of the embodiments. No language in the specification should beconstrued as indicating any unclaimed element as essential to thepractice of the embodiments.

In the following description, it is understood that terms such as“first,” “second,” “top,” “bottom,” “up,” “down,” and the like, arewords of convenience and are not to be construed as limiting terms.Thus, particularly, recitation of first and second should not beconstrued to imply any particular order.

Referring now to FIG. 1A, a stereolithography system 100 can be used toform a three-dimensional object 102 from a resin 104 by selectivelyexposing the resin 104 to activation energy from an activation lightsource 114. The resin 104 can include particles (e.g., metal, ceramic,or a combination thereof) suspended in a plurality of binders, which caninclude a first binder and a second binder. While the resin 104 caninclude the first binder and the second binder, it should be appreciatedthat the resin 104 can include a greater number of binders withoutdeparting from the scope of the present disclosure.

In general, the second binder can be different from the first binder andin a mixture with the first binder to form the resin 104 withcharacteristics particularly suitable for stereolithographic fabricationof dense objects. For example, as described in greater detail below, atleast one of the first binder and the second binder can have anincreased resistance to deformation upon exposure to light having apredetermined wavelength, and the first binder and the second binder canbe separately extractable from the three-dimensional object 102. Thus,for example, the first binder and the second binder, in combination, canaddress the challenges of handling the resin 104 in thestereolithography system 100 while having mechanical and/or chemicalproperties useful for forming the three-dimensional object 102. Throughlayer-by-layer exposure of the resin 104 to activation light, a greenpart, such as the three-dimensional object 102, can be formed. As alsodescribed in greater detail below, the first binder and the secondbinder can be extracted (e.g., separately extracted) from thethree-dimensional object 102, and the three-dimensional object 102 canbe densified to form a finished part. As compared to a part formed onlyfrom polymeric materials, it should be appreciated that the resultingfinished part formed through densification of the particles of the resin104 can have improved strength, particularly in instances in which theparticles include metal and/or ceramic material.

The stereolithography system 100 can be an inverted system including amedia source 106 and a build plate 108. The inverted orientation of thestereolithography system 100 can facilitate, among other things,draining excess amounts of the resin 104 from the three-dimensionalobject 102 and back toward the media source 106 under the force ofgravity. In use, the media source 106 can carry the resin 104, and thebuild plate 108 can move in a direction away from the media source 108as the three-dimensional object 102 is built through layer-by-layerexposure of the second binder in the resin 104 on the media source 106to activation light. More specifically, the stereolithography system 100can include a build chamber 110 defining a working volume 112, in whichthe media source 106 and the build plate 108 can be disposed, and thestereolithography system 100 can include an activation light source 114positioned to direct activation light, as described in greater detailbelow, into the working volume 112 in a direction toward the mediasource 106 and the build plate 108. Continuing with this example, lightfrom the activation light source 114 can be controlled to be incident onthe resin 104 carried by the media source 106 to modify the secondbinder in the resin 104 in a predetermined pattern to form a layer ofthe three-dimensional object 102 on a substrate (e.g., the build plate108 or a previous layer of the three-dimensional object 102).

The stereolithography system 100 can include a heater 116 a,b in thermalcommunication with the media source 106 and controllable to heat themedia source 106 to a first target temperature (e.g., greater than about50° C.), thus heating the resin 104 carried by the media source 106. Thefirst target temperature can be, for example, greater than a melttemperature of the first binder of the resin 104. Thus, heating themedia source 106 can facilitate spreading the resin 104 on the mediasource 106 prior to activating the second binder of the resin 104 and,further or instead, can facilitate removal of the first binder followingactivation of the second binder of the resin 104.

The heater 116 a,b can be any type and number of heaters sufficient tocreate a desired thermal profile within the working volume 112.Accordingly, the heater 116 a,b can be spatially distributed in theworking volume 112. Additionally, or alternatively, the heater 116 a,bcan transfer heat within the working volume 112 through conduction,forced convection, natural convection, radiation, or combinationsthereof. As used herein, conduction includes heat transfer through amedium that is solid, semi-solid, liquid, or combinations thereof. Thus,for example, heat transfer from the media source 106 to the resin 104should be understood to occur primarily through conduction. Also, asused herein, convection includes heat transfer through a gaseous medium.Accordingly, heat transfer from air or another gaseous medium in theworking volume 112 to the three-dimensional object 102 should beunderstood to occur primarily through convection. More generally, itshould be understood that a description of a primary mode of heattransfer should not be understood to foreclose the possibility of othermodes of heat transfer, unless explicitly stated or made clear from thecontext.

An example of heater 116 a,b includes a resistance heater 116 a inthermal communication with the media source 106. For example, theresistance heater 116 a can be embedded in the media source 106. Heatcan be transferred from the resistance heater 116 a, through the mediasource 106, and into the resin 104 carried by the media source 106. Heattransfer from the resistance heater 116 a to the resin 104 can occurprimarily through conductive heat transfer, and the resistance heater116 a can be controlled to control the temperature and, thus, one ormore properties (e.g., flowability) of the resin 104.

In certain implementations, the resistance heater 116 a can beadditionally, or alternatively, in thermal communication with the buildplate 108 such that heat can be transferred (e.g., primarily throughconductive heat transfer) from the resistance heater 116 a, through thebuild plate 108, and into the three-dimensional object 102. As comparedto a build plate that is not heated, heating the build plate 108 canreduce thermal gradients experienced by the three-dimensional object 102during fabrication. For example, the temperature of the build plate 108can be controlled to a temperature substantially similar to atemperature of the media source 106. In instances in which theresistance heater 116 a heats the build plate 108 and the media source106, portions of the resistance heater 116 a heating each of thesecomponents can be separately controllable and/or spatially separated asnecessary to achieve a desired thermal profile along the media source106 and the build plate 108.

As an additional, or alternative, example, the heater 116 a,b caninclude an ambient heater 116 b spaced from the media source 106 (e.g.,in a portion of the working volume 112 above the media source 106).Spacing of the ambient heater 116 from the media source 106 can beuseful, for example, for facilitating separate control of thetemperature of a gaseous medium (e.g., air) in the working volume 112relative to the temperature of the resin 104 carried on the media source106. The ambient heater 116 b can be, for example, a forced convectionheater, such as a heater including a fan moving air over a heatingelement, arranged to move heated gas along the portion of the workingvolume 112 away from the media source 106. In certain implementations,the ambient heater 116 b can be disposed within the working volume 112to facilitate efficient heating of the working volume 112. In someimplementations, the ambient heater 116 b can be disposed outside of theworking volume 112 and in thermal communication with the working volume112 through one or more ducts (or similar conduits) to reduce, forexample, thermal stress on components of the ambient heater 116 b.

The heater 116 a,b can be controllable (e.g., separately controllablefrom the heat provided to the media source 106) to heat a gaseous mediumin a portion of the working volume 112 away from (e.g., above) the mediasource 106 to a second target temperature. In implementations in whichthe second target temperature is an elevated temperature (e.g., greaterthan about 50° C.), heating the gaseous medium in the portion of theworking volume away from the media source 106 can maintain the firstbinder of the resin 104 in a molten state to facilitate, for example,draining the first binder from the three-dimensional object 102 as thethree-dimensional object 102 is built through layer-by-layer activationof the second binder of the resin 104. Additionally, or alternatively,heating the gaseous medium in the portion of the working volume awayfrom the media source 106 can be useful for controlling thermalgradients experienced by the three-dimensional object 102 as a portionof the three-dimensional object 102 is near or in contact with the resin104 at the first target temperature while another portion of thethree-dimensional object 102 is away from the resin 104. That is,heating gaseous medium in the portion of the of the working volume awayfrom the media source 106 to the second target temperature canfacilitate maintaining the temperature of the three-dimensional object102 relatively uniform during the fabrication process. This relativethermal uniformity maintained in the three-dimensional object 102 can,for example, reduce warping or other types of deformation that canotherwise occur in the presence of large thermal gradients.

In certain implementations, the second target temperature correspondingto the gaseous medium in the portion of the working volume away from themedia source 106 can be the same or about the same (e.g., within about±5° C.) as the first target temperature of the media source 106 suchthat the three-dimensional object 102 and the resin 104 carried by themedia source 106 are at the same or about the same temperature. In suchinstances, the repeated introduction and removal of thethree-dimensional object 102 into a molten form of the resin 104 can beless likely to create local solidification of one or both of the firstbinder and the second binder of the resin 104. Because such localsolidification can interfere with fabrication of the three-dimensionalobject 102, maintaining the second target temperature to be about thesame as the first target temperature can improve accuracy of thethree-dimensional object 102 being formed.

The stereolithography system 100 can include one or more temperaturesensors to facilitate controlling the heater 116 a,b to achieve adesired thermal profile within the working volume 112. For example, thestereolithography system 100 can include a temperature sensor 118disposed in a portion of the working volume 112 away from the mediasource 106. The temperature sensor 118 can be, for example, athermocouple or any one or more of various different types oftemperature sensors known in the art and suitable for measuring anindication of temperature in an environment. The heater 116 a,b can becontrollable (e.g., through feedback control) based on a signal receivedfrom the temperature sensor 118 to heat the gaseous medium in a portionof the working volume 112 away from the media source 106.

While the working volume 112 can be heated in various different ways toachieve any one or more of the various different advantages describedherein, it should be appreciated that certain portions of thestereolithography system 100 can be advantageously thermally isolatedfrom the working volume 112 and/or from the heater 116 a,b. For example,the activation light source 114 can be thermally isolated from theworking volume 112 and/or the heater 116 a,b to prolong the useful lifeof the activation light source 114.

In general, the activation light source 114 can deliver light of awavelength (e.g., a predetermined wavelength) and exposure time suitableto crosslink and/or polymerize one or both of the first binder and thesecond binder of the resin 104. The activation light source 114 caninclude an ultraviolet light source in implementations in which thesecond binder of the resin 104 undergoes crosslinking and/orpolymerization upon sufficient exposure to ultraviolet light. As a morespecific example, the activation light source 114 can include any one ormore of various different ubiquitous light sources that produce lighthaving a wavelength of about 300 nm to about 450 nm (e.g., about 405 nm,which corresponds to the Blu-ray Disc™ standard). Further, or instead,the activation light source 114 can produce light within the daylightfrequency, and one or both of the first binder and the second binder ofthe resin 104 can include a daylight curable polymer, such as anydaylight curable polymer known in the art.

In certain implementations, the activation light source 114 can have awavelength greater than the average size of particles suspended in theresin 104, which can reduce the likelihood that the particles willinterfere with crosslinking and/or polymerization of one or both of thesecond binder of the resin 104. Such reduced interference can, forexample, advantageously reduce the amount of light exposure timerequired to crosslink and/or polymerize one or both of the first binderand the second binder in the resin 104. Further, or instead, reducedinterference can enhance geometric resolution of the three-dimensionalobject 102 by reducing light scattering.

The activation light source 114 can be controllable to provide a patternof light incident on the resin 104. For example, the activation lightsource 114 can include a laser controlled to rasterize an image on theresin 104. As another, non-exclusive example, the activation lightsource 114 can include a digital light processing (DLP) projectorincluding a plurality of micromirrors controllable to create an image onthe resin 104. As an additional or alternative example, the activationlight source 114 can include one or more light emitting diode (LED)displays.

Light from the activation light source 114 can pass through a portion117 of the media source 106 that is optically transparent to the lightfrom the activation light source 114 such that the presence of theportion 117 of the media source 106 in the light path produces little tono interference with light directed from the activation light source 114to the resin 104 carried by the media source 106. Thus, for example, inimplementations in which the activation light source 114 includes anultraviolet light source, the portion 117 of the media source 106 in thepath of the activation light source 114 can be transparent toultraviolet light. Further, or instead, in implementations in which theactivation light source 114 is disposed outside of the working volume112, light from the activation light source 114 can pass into buildchamber 110 with little to no interference. While the media source 106and/or the build chamber 110 can be optically transparent to light fromthe activation light source 114, it should be appreciated that it may bedesirable, in certain applications, to use one or both of the mediasource 106 and the build chamber 110 to filter light from the activationlight source 114.

The stereolithography system 100 can include a controller 120 (e.g., oneor more processors) and a non-transitory, computer readable storagemedium 122 in communication with the controller 120 and having storedthereon computer executable instructions for causing the one or moreprocessors of the controller 120 to carry out the various methodsdescribed herein. For example, the controller 120 can be incommunication with one or more of the build plate 108, the activationlight source 114, the heater 116 a,b, and the temperature sensor 118 tocontrol fabrication of the three-dimensional object 102 based on athree-dimensional model 124 stored on the computer readable storagemedium 122. In certain instances, the stereolithography system 100 canfurther include a camera and vision system that can detect parameters(e.g., dimensions) of the three-dimensional object 102 as it is formed,and the computer-readable storage medium 122 can store a digital twin126 of the three-dimensional object 102 such that variations and defectsof the three-dimensional object 102 can be evaluated.

In general, the resin 104 can be responsive to light, heat, or acombination thereof controlled by the controller 120 such that one orboth of the first binder and the second binder can be controllablyhandled and modified. As a specific example, the controller 120 cancontrol heat to facilitate spreading the resin 104 along the mediasource 106 and, further or instead, can control light along the mediasource to control a two-dimensional pattern of crosslinking,polymerization, or both, in one or more of the first binder and thesecond binder of the resin 104. The ability to control accurately thedistribution of the resin 104 and crosslinking or polymerization of oneor both of the first binder and the second binder of the resin 104 canadvantageously facilitate controlling a shape of a layer and, thus,controlling dimensional features of the three-dimensional object 102during a stereolithography process.

The resin 104 can include particles suspended in a mixture of the firstbinder and the second binder. Thus, more specifically, the particles canbe suspended in a solution including the first binder and the secondbinder. In general, the particles can be thermally processable tocoalesce with one another, and optionally with additional material, intoa mass. In general, the mass formed through coalescence of the particlescan be denser than the resin and, thus, can include a porous mass or asolid mass. As used herein, thermal processing shall be understood toinclude any manner and form of coalescence of the particles based ondirect or indirect application of heat. Examples, therefore, of thermalprocessing include sintering, infiltration with liquid metal, andthermally-activated pyrolysis of a polymer-derived ceramic. Further, ininstances in which thermal processing includes sintering, such thermalprocessing shall be understood to include one or more of pre-sintering,solid state sintering, liquid phase sintering, transient liquid phasesintering, and, more generally, any manner and form of sintering knownin the art.

At least one of the first binder and the second binder can be reactiveto crosslink or polymerize upon sufficient exposure of the first binderand the second binder to a predetermined wavelength of light from theactivation light source 114. Such crosslinking or polymerization can,for example, increase the resistance of the respective binder todeformation. That is, crosslinking or polymerizing at least one of thefirst binder and the second binder can facilitate maintaining a shape ofthe three-dimensional object and, accordingly, can improve reduce thelikelihood of unintended deformation of the three-dimensional object asthe three-dimensional object undergoes post-processing to form afinished part.

In certain implementations, the first binder and the second binder caneach be separately extractable from a coalesced mass of the particlesforming the three-dimensional object 102. That is, the first binder canbe removable from the particles through a first debinding process, andthe second binder can be removable from the particles through a seconddebinding process, which can be different from the first debindingprocess and/or temporally separate from the first debinding process.

The physical properties of the first binder and the second binder can bechanged through a selective and controlled application of energy (e.g.,light, heat, or a combination thereof) during a stereolithographicprocess to address different requirements associated with differentstages of the stereolithographic process, such as handling (e.g.,spreading) the resin 104, forming the three-dimensional object 102layer-by-layer, and finishing the three-dimensional object 102 into adense part formed primarily of the particles. For example, as describedin greater detail below, the first binder and the second binder can havedifferent melt temperatures to facilitate, among other things,decoupling spreading characteristics of the resin 104 from bindingcharacteristics of the resin 104. Additionally, or alternatively, thefirst binder and the second binder can have different responses toincident light. That is, continuing with a more specific example, thefirst binder can be substantially non-reactive under exposure towavelengths of light sufficient to crosslink or polymerize the secondbinder such that the physical properties of the second binder can bechanged during a stereolithographic process without significantlychanging the physical properties of the first binder.

The suspension of particles in the resin 104 can include a dispersion ofparticles in a solid or a molten form of a mixture of the first binderand the second binder. The dispersion of the particles can be uniform orsubstantially uniform (e.g., varying by less than about ±10 percent)within the mixture of the first binder and the second binder. Moregenerally, however, the degree of uniformity of the particles can be afunction of strength and/or design tolerances acceptable for thefabrication of a finished part formed from the three-dimensional object102.

The first binder and the second binder can be, for example, misciblewith one another such that the mixture of the first binder and thesecond binder is homogenous. Alternatively, the first binder and thesecond binder can be immiscible with one another. In such instances, thedispersion of the particles in the mixture of the first binder and thesecond binder can be formed or made more homogeneous by shaking orotherwise agitating a molten form of the resin 104 prior to or during astereolithography process.

One or both of the first binder and the second binder can be a lowmolecular weight material (e.g., a monomer or an oligomer), with the lowmolecular weight indicative of a low degree of crosslinking orpolymerization. For example, one or both of the first binder and thesecond binder can have a molecular weight of less than about 1000 g/mol.Continuing with this example, the molecular weight of the respectivebinder can be increasable from less than about 1000 g/mol to greaterthan about 1000 g/mol (e.g., greater than about 2000 g/mol) underexposure to the predetermined wavelength of light sufficient tocrosslink or polymerize the second binder. The resulting crosslinking orpolymerization associated with such an increase in molecular weight ofthe respective binder can correspond to curing of the respective bindersuch that the resin 104 in a respective layer takes a relatively stableshape during fabrication of the three-dimensional object 102.

The first binder and the second binder can have different melttemperatures to facilitate handling the resin 104 in certainimplementations. For example, the first binder can have a first melttemperature and the second binder can have a second melt temperatureless than or about equal to the first melt temperature. In suchinstances, the flow of the resin 104 can be controlled by controllingtemperature of the resin 104 relative to the melt temperature of thefirst binder. As a more specific example, the first binder can have afirst melt temperature less than about 80° C., and the temperature ofthe media source 106, the build plate 108, and/or the working volume 112can be controlled to be above about 80° C. such that the resin 104 ismolten prior to receiving incident light from the activation lightsource 114. Additionally, or alternatively, the first binder can have amelt temperature above about 25° C. such that the resin 104 can besubstantially solid (e.g., in the form of a paste) to facilitate storingthe resin 104 in a stable form—with the particles suspended in the firstbinder and the second binder—for a significant period of time, such asmultiple weeks or longer. In certain implementations, the concentrationof the particles suspended in the mixture of the first binder and thesecond binder can be such that the resin 104 is a non-Newtonian fluid at25° C.

Additionally, or alternatively, the first binder and the second bindercan have different decomposition temperatures. For example, the firstbinder can have a first decomposition temperature, and the second bindercan have a second decomposition temperature greater than the firstdecomposition temperature such that the second binder can generallywithstand heating to a greater temperature. For example, the secondbinder can remain in the three-dimensional object 102 as thethree-dimensional object 102 is heated further, after the first binderis thermally debound from the three-dimensional object 102 through aprimary debinding process.

In general, the first binder can be extractable from the second binderand/or the material of the particles forming the three-dimensionalobject 102 through a primary debinding process, which can include any ofvarious different processes suited to the composition of the firstbinder and compatible with separately extracting the second binder fromthe three-dimensional object 102 through a secondary debinding process.For example, the first binder can include a wax extractable from thesecond binder by chemical solvation in a non-polar chemical followingexposure of the second binder to wavelengths of light sufficient tocrosslink or polymerize the second binder. As another, non-exclusiveexample, the first binder can include a plurality of low-molecularweight constituents (e.g., paraffin wax and steric acid), eachconstituent extractable from the second binder by the same chemicalsolution (e.g., hexane) following exposure of the second binder towavelengths of light sufficient to crosslink or polymerize the secondbinder. Additionally, or alternatively, the first binder can includepolyethylene glycol extractable from the second binder by dissolution bywater or alcohols following exposure of the second binder to wavelengthsof light sufficient to crosslink or polymerize the second binder. Stillfurther in addition, or in the alternative, the first binder can includea wax extractable from the second binder by supercritical carbon dioxidefluid following exposure of the second binder to wavelengths of lightsufficient to crosslink or polymerize the second binder. Yet further inaddition, or yet further in the alternative, the first binder caninclude a low molecular weight polyoxymethylene extractable from thesecond binder by catalytic debinding in nitric oxide vapor. For example,the polyoxymethylene can melt at a temperature substantially similar toa temperature at which the second binder is photopolymerizable. Incertain implementations, the first binder can include polyanhydrideextractable from the second binder by hydrolysis and dissolution inaqueous solution following exposure of the second binder to wavelengthsof light sufficient to crosslink or polymerize the second binder. Insome implementations, the first binder can include a wax thermallyextractable from the second binder following exposure of the secondbinder to wavelengths of light sufficient to crosslink or polymerize thesecond binder. The thermal extraction can include, as an example,boiling the wax at a temperature at which the second binder remainssubstantially intact (e.g., substantially retaining its shape) in thethree-dimensional object 102.

The second binder can be removable from the first binder and/or from thematerial of the particles forming the three-dimensional object 102through a secondary debinding process, which can include any of variousdifferent processes suited to the composition of the second binder. Forexample, the second binder can be debindable from the three-dimensionalobject 102 by cleaving and/or un-polymerizing the second binder (e.g.,through one or more of hydrolyzing or solvolyzing) followingcrosslinking or polymerization of the second binder. As a more specificexample, the second binder can include acetal diacrylate, which can beextractable from the first binder by catalytic debinding in nitric oxidevapor following exposure of the second binder to a wavelength of lightsufficient to crosslink or polymerize the second binder. As anadditional or alternative example, the second binder can includeanhydride diacrylate, which can be extractable from the first binder byhydrolysis and dissolution in one or more aqueous solutions followingexposure of the second binder to the wavelength of light sufficient tocrosslink or polymerize the second binder. Yet further in addition, orfurther in the alternative, the second binder can include a saccharidediacrylate (e.g., monosaccharide diacrylate, disaccharide diacrylate, ora combination thereof), each of which can be extractable from the firstbinder by hydrolysis in one or more aqueous solutions including acatalyst (e.g., a catalyst including one or more biological enzymes,such as amylase) for hydrolysis of the crosslinked or polymerized secondbinder following exposure of the second binder to the wavelength oflight sufficient to crosslink or polymerize the second binder.Additionally, or alternatively, in instances in which the second binderis debindable by cleaving and/or un-polymerizing the second binder, thefirst binder can have a high molecular weight (e.g., greater than about1000 g/mol) and be present in a small volume percentage (e.g., less thanabout 10 percent) in the resin 104.

In certain implementations, the first binder and the second binder bothcan be crosslinked or polymerized through sufficient exposure to lightof a predetermined wavelength. In such implementations, the primarydebinding process associated with extracting the first binder from thesecond binder and/or from the material of the particles forming thethree-dimensional object 102 can include breaking down the crosslinkedor polymerized first binder while the second binder remains cross-linkedor polymerized in the three-dimensional object 102. As a specificexample, the primary debinding process can include applying a catalyticsolution to the three-dimensional object to cause part of the firstbinder to depolymerize, dissolve, or otherwise breakdown. An example ofa first binder that can react to light and can be subsequently brokendown in this way include anhydride and methacrylic anhydride. Moregenerally, the first binder that can be broken down in this way caninclude a small molecule with two acylate groups (a diacrylate)containing one or more anhydride linkages. Continuing with this example,the acrylates can polymerize upon exposure to ultraviolet light, and theanhydride linkages can break down in the presence of water and othermolecules.

The particles suspended in the resin 104 can include, for example, anyone or more of various different metals. Further, or instead, theparticles can include any one or more of various different ceramics. Tofacilitate producing a solid part with substantially uniform strengthcharacteristics along the part, the particles can have the samecomposition. Additionally, or alternatively, the particles have asubstantially uniform size. In certain implementations, the particlescan include nanoparticles (e.g., particles having an average particlesize of greater than about 1 nanometer and less than about 100nanometers). The nanoparticles can facilitate thermally processing thethree-dimensional object 102 to form a finished part. As a specificexample, the nanoparticles can facilitate sintering thethree-dimensional object 102 at a lower temperature.

In certain instances, the particles can have an average size less than awavelength of light sufficient to crosslink or polymerize one or both ofthe first binder and the second binder, which can have any of variousdifferent advantages described herein. For example, such a ratio ofparticle size to the wavelength of light can reduce the likelihood thatparticles in the resin 104 will interfere with the incident light, whichcan result in shorter times associated with crosslinking or polymerizingone or both of the second binder. This reduction in time can, in turn,reduce the time associated with forming a finished part, which can beparticularly useful for mass production of parts.

In certain instances, it can be desirable to have a high concentrationof the particles in the resin 104 and, thus, a comparatively lowerconcentration of the first binder and the second binder in the resin104. A high concentration of the particles in the resin 104 can, forexample, reduce the amount of the first binder and/or the second binderin the resin 104, therefore reducing the time and/or energy required tocrosslink or polymerize one or both of the first binder and secondbinder in the resin 104. Additionally, or alternatively, a highconcentration of the particles in the resin 104 can reduce the amount ofeach of the first binder and the second binder in the resin 104, whichcan reduce the amount of time required for extracting the first binderand the second binder from the three-dimensional object 102. As aspecific example of a high concentration, the concentration (by volume)of the particles in the resin 104 can be within ±25 percent of the tapdensity of the particles. As used herein, the tap density of particlesis the bulk density of a powder of the particles after a compactionprocess specified in ASTM B527, entitled “Standard Test Method for TapDensity of Metal Powders and Compounds,” the entirety of which isincorporated herein by reference.

In some implementations, the particles in the resin 104 can includemodified surfaces. With these modified surfaces, the particles canexhibit one or more physicochemical characteristics that differadvantageously from the corresponding one or more physicochemicalcharacteristics of the underlying material of the particles. Forexample, the particles can include chemically functionalized surfacessuch as surfaces having a metal oxide coating useful for resistingcorrosion or other undesired chemical reactions. Additionally, oralternatively, the particles can include functional groups useful forresisting settling of the particles in a mixture of the first binder andthe second binder through steric hindrance. In certain instances, underambient conditions (e.g., in air at about 25° C. at atmospheric pressureand with relative humidity of 20-80%), the particles suspended in themixture of the first binder and the second binder in the resin 104 canhave a timescale of settling of greater than about two weeks, which canfacilitate storing the resin 104 in a stable form for a useful period oftime. In some instances, the settling time of the particles in the resin104 can be greater than the amount of time at which the first binder ismolten during the stereolithography process to reduce the likelihood ofunintended settling of the particles as the three-dimensional object 102is formed.

The resin 104 can, further or instead, include one or more of aphoto-absorber (e.g., a Sudan dye) or a photo-initiator suspended in themixture of the first binder and the second binder. Inclusion of one ormore of a photo-absorber or a photo-initiator can facilitate, forexample, tuning the resin 104 to achieve a particular response (e.g., atarget curing time for one or more of the first binder or the secondbinder) upon exposure to activation light from the activation lightsource 114.

The volumetric composition of the resin 104 can be a function of, amongother things, the composition of the constituent components of the resin104. In certain implementations, the second binder can be about 10percent to about 50 percent by volume of the total volume of the resin104. The first binder can include, for example, one or more of thefollowing: paraffin wax, carnauba wax, stearic acid, polyethyleneglycol, polyoxymethylene, oleic acid, and dibutyl phthalate. The secondbinder can include, for example, one or more of the following:poly(methyl methacrylate), polyethylene glycol diacrylate, urethaneoligomers functionalized to acrylate groups, epoxy oligomersfunctionalized to acrylate groups, 1,6-Hexanediol acrylates, or styrene.Additionally, or alternatively, the resin 104 can include one or more ofthe following mixed with the first binder, the second binder, and theparticles: ethylene vinyl acetate, a slip agent (e.g., stearic acid),and/or a compatibilizer (e.g., metal stearate (e.g., zinc stearate),stearic acid, or a combination thereof). In an exemplary formulation,the first binder can include polyethylene glycol and the second bindercan include poly(methyl methacrylate). For example, polyethylene glycolcan be about 40-90 percent of the combined weight of the first binderand the second binder and poly(methyl methacrylate) can be about 10-60percent of the combined weight of the first binder and the secondbinder. In another exemplary formulation, the first binder can includeparaffin wax and the second binder can include a waxy or hydrophobicdiacrylate oligomer.

FIG. 2 is a flowchart of an exemplary method 200 of fabricating athree-dimensional object using any one or more of the various differentstereolithography systems described herein. For example, the exemplarymethod 200 can be implemented as computer-readable instructions storedon the computer-readable storage medium 122 (FIG. 1) and executable bythe controller 120 (FIG. 1) to operate the stereolithography system 100(FIG. 1) to form the three-dimensional object 102 (FIG. 1).

As shown in step 202, the exemplary method 200 can include providing aresin to a media source. The media source can be, for example, disposedwithin a working volume defined by a build chamber. Further, or instead,the resin can be any of the various different resins described hereinand, thus, can include particles suspended in a mixture of a firstbinder and a second binder.

Providing the resin to the media source can include depositing the resinon the media source. For example, the resin can be moved through adispensing section, such as a nozzle, of the media source, and thedispensing section can be, optionally, heated to a temperature greaterthan the melt temperature of the first binder of the resin such that theresin becomes molten to facilitate flow through the dispensing sectionand spreading along the media source. Providing the resin to the mediasource can additionally, or alternatively, include moving a solidfeedstock of the resin into a working volume of the stereolithographysystem. For example, the feedstock can be moved into the working volumefrom a storage container thermally isolated from the working volume.Such thermal isolation can be useful, for example, for maintaining thefeedstock in a solidified form such that the particles of the resin canremain suspended for a substantial period of time. More generally,providing the resin to the media source can include moving the resinwith any one or more of the fabrication systems described herein, suchas any one or more of the fabrication systems described below.

Providing the resin can include dispersing the resin to form a layer ofresin on a substrate. The thickness of the layer of resin can representthe resolution of the stereolithography process and, thus, a small layerthickness can be useful for fabricating parts with a high degree ofspatial resolution (e.g., fewer errors). Also, or instead, a small layerof thickness can be useful for increasing the likelihood that activationlight can sufficiently penetrate the layer to activate at least one ofthe first binder and the second binder along the depth of the layer. Incertain implementations, the layer of the resin can be, for example,less than about 200 μm.

As shown in step 204, the exemplary method 200 can, optionally, includeheating the media source to a first target temperature. The first targettemperature can be greater than a melt temperature of a first binder(e.g., greater than about 50° C.). It should be understood that heatingthe media source to the first target temperature can be useful formaintaining the resin in a molten form, which can facilitate spreadingthe resin along the media source. Heating the media source can includeany of the various different heating methods described herein and, thus,can include conductively heating the media source (e.g., through aresistance heater in contact with or embedded in the media source).

In certain implementations, the exemplary method 200 can additionally,or alternatively, include heating a gaseous medium in a portion of theworking volume away from the media source to a second target temperature(e.g., greater than about 50° C.) according to any of the variousdifferent methods described herein. The light energy can be directed ina predetermined pattern onto a layer of resin with the air in theportion of the working volume away from the media source at the secondtarget temperature, which can be useful for reducing thermal gradientsin the three-dimensional object being fabricated, as described herein.

As shown in step 206, the method can include directing light energy tothe media source. For example, the light energy can be directed to themedia source with the media source at the first target temperature and,thus, with the first binder in a molten state. The light energy can bereceived from any of the various different activation light sourcesdescribed herein and, therefore, can include light energy in or near theultraviolet range.

The light energy can be directed to the media source, and thus to theresin, in a predetermined pattern corresponding to dimensions receivedfrom a three-dimensional model forming the basis of thethree-dimensional object being fabricated. The light energy can be madeincident on the media source, and thus on the resin, for a timesufficient for at least one of the first binder and the second binder toundergo modification, such as any one or more modifications describedherein. Further or instead, the step 206 of directing light energy canbe repeated as necessary to direct light energy onto each layer of aplurality of layers of the resin to cure the resin on a substratecarried by the build plate. The light energy can be directed onto theresin in a respective predetermined pattern associated with therespective layer to form the three-dimensional object.

As shown in step 208, the exemplary method 200 can include thermallyprocessing particles in the three-dimensional object according to anyone or more of the thermal processes described herein. Thus, thermallyprocessing the particles can include any manner and form of applyingheat to densify the three-dimensional object (e.g., with thedensification including coalescence of the particles with one anotherand, optionally with one or more other materials, to form a mass). Forexample, thermally processing the particles in the three-dimensionalobject can include sintering the particles. Further, or instead,thermally processing the particles in the three-dimensional object caninclude infiltrating the three-dimensional object with a liquid metal.Still further or instead, thermally processing the particles in thethree-dimensional object can include thermally-activated pyrolysis of apolymer-derived ceramic. In general, thermally processing the particlescan be carried out in a post-processing station, as described in greaterdetail below.

As shown in step 210, the exemplary method 200 can include extracting afirst binder from the three-dimensional object. The extraction of thefirst binder from the three-dimensional object can be carried out in aprimary debinding step that leaves substantially all of the secondbinder and the material of the particles remaining in thethree-dimensional object. The primary debinding process can include anyone or more debinding processes known in the art and, therefore, caninclude one or more of thermal debinding and chemical debinding (whichcan include catalytic debinding), as appropriate based on thecomposition of the first binder.

Referring now to FIGS. 1 and 3, an additive manufacturing system 300 caninclude the stereolithography system 100, a conveyor 304, and apost-processing station 306. In use, the three-dimensional object 102,in the form of a green part, can be moved along the conveyor 304 andinto the post-processing station 306, where the first binder and thesecond binder can be extracted from the three-dimensional object 102and/or where the three-dimensional object 102 can undergo thermalprocessing to form a final part. As an example, the three-dimensionalobject 102 can undergo one or more of thermal debinding and chemicaldebinding to remove the first binder and the second binder from thethree-dimensional object 102.

In certain implementations, the three-dimensional object 102 can undergoone or more thermal processes in the post-processing station 306. Forexample, the three-dimensional object 102 can be sintered in thepost-processing station 306. In addition to densifying thethree-dimensional object 102, sintering can alter chemical properties ofthe particles, which can be useful for transforming certain types ofparticles to a metal or to an additive in a metallic alloy in thefinished part. Further, or instead, thermally processing thethree-dimensional object 102 in the post-processing station 306 caninclude infiltrating the three-dimensional object 102 with a liquidmetal. The infiltration of the liquid metal into the three-dimensionalobject 102 can include, for example, movement of the liquid metal intospaces in the three-dimensional object 102 through wicking. In someinstances, infiltrating the three-dimensional object 102 with the liquidmetal can include replacing the first binder and the second binder withthe liquid metal. Additionally, or alternatively, thermally processingthe three-dimensional object 102 can include thermally activatedpyrolysis of a polymer-derived ceramic (e.g., as described in greaterdetail below with respect to FIG. 16).

While the post-processing station 306 is shown as being separate fromthe stereolithography system 100, it should be appreciated that some orall of the post-processing station 306 can be incorporated into thestereolithography system 100 such that any one or more ofpost-processing steps described herein can occur in thestereolithography system 100.

While certain embodiments have been described, other embodiments areadditionally or alternatively possible.

For example, while a build plate has been described, it should beappreciated that the build plate of any of the various differentstereolithography systems described herein can include additional oralternative features. For example, referring now to FIG. 4, a buildplate 408 can be useful for reducing errors in fabricatingthree-dimensional objects. Unless otherwise specified or made clear fromthe context, the build plate 408 should be understood to beinterchangeable with the build plate 108 (FIG. 1) for use in thestereolithography system 100.

The build plate 408 can include a build surface 410 and a coating 412disposed along the build surface 410. The coating 412 can be adherableto any of the various different resins described herein (e.g., the resin104 in FIG. 1). For example, the coating 412 can be adherable to theresin following exposure of the resin to light sufficient to crosslinkand/or polymerize one or both of the first binder and the second binder.Thus, continuing with this example, the coating 412 can be adherable toa three-dimensional object being formed on the build surface 410 (e.g.,the three-dimensional object 102 of FIG. 1). Further, or instead, theresin can be preferentially adherable to the coating 412 on the buildsurface 410 over adherence to a media source (e.g., the media source 106in FIG. 1), increasing the likelihood that the resin will tend to movewith the build plate 408 as the build plate 408 is moved away from themedia source. Accordingly, as compared to a system without a coating,the coating 412 can reduce the likelihood of fabrication errors thatwould otherwise result from improper or insufficient adherence of theresin to the build plate 408.

The coating 412 can include, for example, a first binder, a secondbinder, or a combination thereof to facilitate adhering the resinincluding the first binder and the second binder to the coating 412.More specifically, the coating 412 can include the first binder, thesecond binder, or a combination thereof, and can be substantially freeof the particles of the resin to further improve adhesion between thecoating 412 and the resin used for a particular stereolithographyfabrication.

The coating 412 can be provided to the build surface 410 from a coatingsource at the start of a new build, such as before a first layer of athree-dimensional object is formed on the build plate 408. For example,the coating source can include a film of the coating 412 positionable onthe build surface 410 at the start of a new build. Additionally, oralternatively, the coating source can include a reservoir of the coating412, from which the coating 412 can be drawn and delivered (e.g.,through a nozzle) to the build surface 410. Further, or instead, thecoating can be manually positioned on the build surface 410 as part of aset-up process.

As another example, while stereolithographic systems have been describedas including certain modes of delivery of a resin to a media source,other delivery modes are additionally or alternatively possible. Forexample, referring now to FIG. 5, a stereolithography system 500 isanalogous to the stereolithography system 100 (FIG. 1), except asdescribed below or made clear from the context. The stereolithographysystem 500 can include a film 502 movable within a working volume tomove resin to a media source, where incident light from an activationlight source can activate a binder in the resin to form a layer of athree-dimensional object. Examples of materials that can be used to formthe film 502 include, but are not limited to: polypropylene,polytetrafluoroethylene, and polydimethylsiloxane. More generally, thefilm 502 can be substantially transparent to activation light used tocrosslink or polymerize one or both of the first binder or the secondbinder such that the film 502 can be disposed between an activationlight source and the resin without interfering with activation of thefirst binder and/or the second binder in the resin.

In certain implementations, the film 502 can be indexed to provide a newlayer of the resin along the media source at the beginning of the buildof each layer. For example, between each layer, the film 502 can beindexed according to a dimension of the media source. Additionally, oralternatively, the film 502 can be dynamically indexed such that an areaof the film 502 corresponding to resin used in an immediately precedinglayer is moved beyond the media source prior to building an immediatelysubsequent layer. Further, or instead, dispersing the resin canadditionally or alternatively include the use of a roll-to-rollconfiguration in which a roll of the resin is brought into contact witha roll of the film 502 such that the resin becomes dispersed on the film502.

As still another example, while stereolithographic systems have beendescribed as being inverted, additional or alternative configurationsare possible. For example, referring now to FIG. 6, a stereolithographysystem 600 is analogous to the stereolithography system 100 (FIG. 1),except as described below or made clear from the context. Thestereolithography system 600 can be oriented such that a build platemoves downward, into a media source, as a three-dimensional object isformed layer-by-layer.

As yet another example, stereolithographic systems can additionally, oralternatively, include configurations for shearing discrete portions ofeach layer of a three-dimensional object being formed. For example,light energy can be delivered to discrete portions of any one or more ofthe resins described herein to cure the resin, and the cured resin inthe respective discrete portion can be sheared independently of shearingthe cured resin in other discrete portions. As used herein, a “curedresin” shall be understood to be a resin, such as any one or more of theresins described herein, including at least one cured binder and mayadditionally include one or more uncured binders.

In general, a layer of a resin carried on a media source can be curedbetween the media source and a substrate carried on a build plate of astereolithographic system, with the layer of the cured resin adhering toboth the substrate and the media source. Before a subsequent layer ofthe resin can be deposited on top of the current layer of cured resin,the current layer of the cured resin is separated from the media source.As a specific example, the current layer of the cured resin can beseparated from the media source through the application of a shear forcebetween the media source and the current layer. In general, however,resins loaded with particles, such as described herein, can decrease theshear strength of the cured resin and, thus, can have an adverse impacton proper separation of the cured binder from the media source. Thus, toreduce the likelihood of improper separation in a cured binder loadedwith particles, stereolithographic systems of the present disclosure canseparate discrete portions of each layer of cured resin from the mediasource. As compared to separating an entire layer of a cured resin froma media source, separating discrete portions of each layer of the curedresin from the media source can facilitate complete separation of thecured resin from the media source, which can correspondingly improveaccuracy of the three-dimensional object formed through successivelybuilding layers of the cured resin on top of one another.

Referring now to FIGS. 7A and 7B, a fabrication system 700 can include amedia source 706, a build plate 708, and an activation light source 714.Unless otherwise specified or made clear from the context, thefabrication system 700 can be part of any one or more of thestereolithography systems described herein. Thus, for example, thefabrication system 700 can be part of the stereolithography system 100(FIG. 1), with media source 706 and the build plate 708 of thefabrication system 700 disposed in the working volume 112 defined by thebuild chamber 110.

The activation light source 714 can be, for example, any one or more ofthe activation light sources described herein. Thus, by way of exampleand not limitation, the activation light source can include a lightsource having a wavelength of about 300 nm to about 350 nm.

The media source 706 can include a transparent portion 715. Theactivation light source 714 can be positioned to direct activation lightinto a working volume (e.g., the working volume 112 in FIG. 1) throughthe transparent portion 715 of the media source 706 toward a surface 717of the build plate 708. In use, as described in greater detail below,the activation light can selectively cure discrete portions of a layerof a resin on a substrate (e.g., the surface 717 of the build plate 708or a previous layer) carried by the build plate 708 in the workingvolume. As also described in greater detail below, one or both of thebuild plate 708 and the transparent portion 715 of the media source 706can be movable relative to one another. The movement of the build plate708 and the transparent portion 715 of the media source 706 relative toone another can, for example, change an origin of a shear force on acured resin between the build plate 708 and the media source 706.

As an example, one or both of the build plate 708 and the transparentportion 715 of the media source 706 can be movable relative to oneanother to change a position of the transparent portion 715 of the mediasource 706 by an increment substantially equal to a width of thetransparent portion 715 of the media source 706 in a direction parallelto the surface 717 of the build plate 708. Through such incrementalmovement of the transparent portion 715 of the media source 706, thetransparent portion 715 of the media source 706 can be moved in adjacentincremental steps in a direction parallel to the surface 717 of thebuild plate 708. As the transparent portion 715 of the media source 706,light energy from the activation light source 714 can cure a layer ofthe resin in discrete portions. More specifically, in a first increment,the light energy from the activation light source 714 can cure a firstdiscrete portion of the layer of resin, in a second increment adjacentto the first increment, the light energy from the activation lightsource 714 can cure a second discrete portion of the layer of resin, andso forth.

The transparent portion 715 of the media source 706 can, for example,span a dimension of the build plate 708. In certain instances, thetransparent portion 715 of the media source 706 can be movable in adirection transverse to (e.g., substantially perpendicular to) thespanned dimension of the surface 717 of the build plate 708.Additionally, or alternatively, the width of the transparent portion 715of the media source 706 can be less than a dimension of the build plate708 in the direction of the changed position of the transparent portion715 of the media source 706 such that a layer of the resin can be curedin multiple discrete portions. Advantageously, each discrete curedportion of the layer of the resin can be separated from the transparentportion 715 (e.g., through the application of a shear force) before thetransparent portion 715 is moved to the next position and the nextdiscrete portion of the layer of the resin is cured. In certainimplementations, the light energy from the activation light source 714can be directed to discrete portions of a given layer of the resin asthe activation light source 714 moves substantially continuously acrossthe given layer of the resin. Similarly, shear force can be applied tothe discrete cured portions of the resin in a substantially continuousmanner. In general, curing and separating discrete portions of a givenlayer of the resin substantially continuously can reduce fabricationtime.

In some implementations, the media source 706 can include a dispersionsection 719, a collection section 721, and a reservoir 723 in fluidcommunication with the dispersion section 719 and the collection section721. The dispersion section 719 can be along a first side of thetransparent portion 715 of the media source 706, and the collectionsection 721 can be along a second side, different from the first side,of the transparent portion 715 of the media source 706. The first sideand the second side can be, for example, opposite one another. In use,resin can be drawn from the reservoir 723 to the dispersion section 719(e.g., through the use of one or more rollers in the reservoir 723). Thedispersion section 719 can include, in some instances, a nozzle (e.g.,shaped as a slit) and, further or instead, can be heated to facilitateflowing the resin through the dispersion section 719 to the transparentportion 715 of the media source 706.

In certain instances, the media source 706 can include a blade 725movable to spread resin from the dispersion section 719 across thetransparent portion 715 of the media source 706. For example, the blade725 can pivot about a point to spread the resin across the transparentportion 715 of the media source 706. Additionally, or alternatively, theblade 725 can be movable to move at least a portion of the resin, suchas excess resin from a previous layer, to the collection section 721.The resin moved to the collection section 721 can be agitated and/orheated to decrease the likelihood that particles in the resin willsettle in the reservoir 723.

While a media source has been described as including a dispensingsection and a collection section on either side of a transparent portionof the media source, other configurations for distributing a resin overa transparent portion of the media source are additionally oralternatively possible. For example, referring now to FIG. 8, a mediasource 806 can include a film 807, an activation light source 814, and atransparent portion 815. Unless otherwise specified or made clear fromthe context, it should be understood that the media source in FIG. 8 canbe used in the fabrication system 700 of FIG. 7A-7B, in addition to orinstead of the media source 706.

In the media source806, a resin can be disposed on the film 807, and thefilm 807 can be movable across the transparent portion 815 of the mediasource 806. For example, the film 807 can be advanced over thetransparent portion 815 of the media source 806 through movement ofrollers 827 on other side of the transparent portion 815. In certaininstances, the film 807 can be indexable by a predetermined width. As aspecific example, the film 807 can be indexable by a width substantiallyequal to the width of the transparent portion 815 of the media source806 such that, as the transparent portion 815 of the media source 806 isincremented in a direction parallel to a build surface (e.g., thesurface 717 in FIG. 7A), the film 807 can be indexed with eachincremental movement of the transparent portion 815 of the media source806. It should be appreciated that, through such indexing of the film807 with incremental movement of the transparent portion 815 of themedia source 806, a fresh panel of resin will be disposed over thetransparent portion 815 of the media source 806 at each increment,before activation light is directed at the resin to cure a discreteportion of a layer of the resin. The film 807 can be formed of any oneor more of the materials described above with respect to the film 502 inFIG. 5. More generally, the film 807 can be understood to be analogousto the film 502 in FIG. 5, unless otherwise specified or made clear fromthe context.

FIG. 9 is a flowchart of an exemplary method 900 of fabricating athree-dimensional object. Unless otherwise specified or made clear fromthe context, the exemplary method 900 can be implemented using any oneor more of the various different stereolithography systems describedherein. For example, the exemplary method 900 can be implemented ascomputer-readable instructions stored on the computer readable storagemedium 122 (FIG. 1) and executable by the controller 120 (FIG. 1) tooperate the stereolithography system 100 (FIG. 1) including one or moreof the fabrication systems of FIGS. 7A, 7B, and 8.

As shown in step 902, the exemplary method 900 can include providingresin to a media source disposed within a working volume defined by abuild chamber. The resin can be any one or more of the resins describedherein, unless otherwise specified or made clear from the context. Moregenerally, the resin can include one or more binders and particles(e.g., metal particles) suspended in the one or more binders. At leastone of the one or more binders can be curable (e.g., crosslinkable orpolymerizable) upon exposure to energy, such as light of a sufficientwavelength. As an example, providing the resin to the media source caninclude moving the resin from a reservoir as described with respect toFIGS. 7A and 7B. Additionally, or alternatively, providing the resin tothe media source can include moving the resin as described with respectto FIG. 8.

As shown in step 904, the exemplary method 900 can include curingdiscrete portions of a layer of the resin on a substrate carried on asurface of a build plate in the working volume. Curing the discreteportions of the layer can include directing light energy into theworking volume through a transparent portion of the media sourceaccording to any one or more of the methods described herein.Accordingly, curing discrete portions of the layer of the resin caninclude curing the layer of the resin in multiple curing steps accordingto any one or more of the discrete curing methods described herein.Thus, for example, during discrete portions of the layer of the resincan include substantially continuously curing adjacent discrete portionsof the layer of the resin and, in concert with such curing, shearing thecured resin in the discrete portions as part of a substantiallycontinuous process. In certain instances, each discrete portion can spana dimension of the surface of the build plate. In such instances, lightenergy can be selectively delivered to a layer of resin by moving thetransparent portion of the media chamber in a single direction (e.g.,transverse to the spanned dimension). Thus, for example, the transparentportion of the media source and the activation light source can bearranged as a substantially elongate light bar (such as the activationlight source 714) that can scan the layer of resin by moving in a singledirection substantially parallel to the surface of the build plate.

As shown in step 906, the exemplary method 900 can include separatingthe cured discrete portions of the layer from the media source. Theseparation of at least one of the cured discrete portions can be doneindependently of separation of at least another one of the cureddiscrete portions. For example, at least one of the cured discreteportions of the layer can be separated from the media source beforeanother one of the cured discrete portions of the layer is formed. As amore specific example, the step 904 of curing and the step 906 ofseparating can be performed alternately as the position of the mediasource is changed relative to the surface of the build plate. Insufficiently rapid succession, alternation of the step 904 of curing andthe step 906 of separating can form the basis of a substantiallycontinuous process applied across a given layer.

In general, separation of the cured discrete portions of the layer fromthe media source can include changing a position of the transparentportion of the media source relative to the build plate (e.g., thesurface of the build plate). The changed position can generate a force(e.g., a shear force) on one or more of the cured discrete portions ofthe layer to separate each corresponding cured discrete portion from themedia source.

In certain instances, one or both of the build plate and the transparentportion of the media source can be movable relative to one another togenerate the force on the one or more cured discrete portions of thelayer. For example, separating the cured portions of the layer from themedia source can include moving one or both of the build plate and thetransparent portion of the media source in a direction having acomponent parallel to the layer of the resin. Additionally, oralternatively, separating the cured discrete portions of the layer fromthe media source can include rotating one or both of the build plate andthe transparent portion of the media source relative to one another. Asone example, one or both of the surface of the build plate and thetransparent portion of the media source can be rotated about an axissubstantially perpendicular to a plane defined by the transparentportion of the media source.

As shown in step 908, the exemplary method 900 can include, for aplurality of layers, repeating the steps of providing resin to the mediasource, curing discrete portions of a given layer, and separating cureddiscrete portions of the layer can be repeated to form each layer of athree-dimensional object.

As shown in step 910, the exemplary method 900 can, optionally, includemoving the build plate (e.g., in a direction away from the media source)before repeating the steps of providing resin to the media source,curing discrete portions of a given layer, and separating cured discreteportions of a given layer. Moving the build plate in this way canprovide spacing necessary for forming a subsequent layer of thethree-dimensional object.

FIG. 10 is a flow chart of an exemplary method 1000 of fabricating athree-dimensional object. Unless otherwise specified or made clear fromthe context, the exemplary method 1000 can be implemented using any oneor more of the various different stereolithography systems describedherein. For example, the exemplary method 1000 can be implemented ascomputer-readable instructions stored on the computer readable storagemedium 122 (FIG. 1) and executable by the controller 120 (FIG. 1) tooperate the stereolithography system 100 (FIG. 1) including one or moreof the fabrication systems of FIGS. 7A, 7B, and 8.

As shown in step 1002, the exemplary method 1000 can include providing aresin to a media source disposed within a working volume defined by abuild chamber. The resin can be, for example, any one or more of theresins described herein, and the media source can be any one or more ofthe media sources of the fabrication systems of FIGS. 7A, 7B, and 8.

As shown in step 1004, the exemplary method 1000 can include curingdiscrete portions of a layer of the resin on a substrate carried by abuild plate in the working volume. In general, curing discrete portionsof the layer of the resin on the substrate can include any one or moreof the methods of curing discrete portions of the layer describedherein. For example, the selective exposure of each discrete segment canbe based on a predetermined pattern associated with the given segment ofthe layer. It should be appreciated that the predetermined patterns ofeach segment combine to form an overall predetermined pattern of thegiven layer.

As shown in step 1006, the exemplary method 1000 can include changingthe position of the transparent portion of the media source relative tothe build plate by an increment substantially equal to a width of thetransparent portion of the media source. The change in position of thetransparent portion of the media source can separate at least one of thecured discrete portions from the media source. In general, changing theposition of the transparent portion of the media source relative to thebuild plate can include any one or more methods of changing the relativeposition of the media source relative to the build plate describedherein. Thus, for example, changing the position of the transparentportion of the media source relative to the build plate can includemoving one or both of the build plate and the media source relative toone another (e.g., to create a shear force in one or more cured discreteportions of the layer of resin). Further, or instead, the transparentportion of the media source can be moved in increments of one width(e.g., with each increment substantially adjacent to a previous positionof the transparent portion) in a direction substantially parallel to thesurface of the build plate as the discrete portions of the layer of theresin are cured for a given layer of a three-dimensional object.

As shown in step 1008, the exemplary method 1000 can include, for eachlayer of a plurality of layers, repeating the steps of providing resinto the media source, curing discrete portions of a given layer, andseparating cured discrete portions of the given layer can be repeated toa three-dimensional object.

As shown in step 1010, the exemplary method 1000 can include moving thebuild plate (e.g., in a direction away from the media source) beforerepeating the steps of providing resin to the media source, curingdiscrete portions of a given layer, and separating cured discreteportions of a given layer.

While certain fabrication systems have been described for deliveringresin to discrete planar portions of a layer and curing each discreteplanar portion of the given layer, other configurations are additionallyor alternatively possible. For example, referring now to FIG. 11, afabrication system 1100 can be based on delivering resin and curingresin along a region of tangential contact between a rolling member anda substrate upon which a given layer is being formed. The fabricationsystem 1100 can include media source 1102, a build plate 1104, and anactivation light source 1106. Unless otherwise specified or made clearfrom the context, the fabrication system 1100 can be part of any one ormore of the stereolithography systems described herein. Thus, forexample, it should be understood that the fabrication system 1100 can bepart of the stereolithography system 100 (FIG. 1) and, therefore, themedia source 1102 and the build plate 1104 of the fabrication system1100 can be disposed in the working volume 112 defined by the buildchamber 110.

The activation light source 1106 can be positioned to direct activationlight, through the media source 1102, toward a surface of the buildplate 1104. The activation light source 1106 can be, for example, any ofthe various different light sources described herein. Light energymoving from the activation light source 1106 can pass through atransparent portion 1110 of the media source 1102 and, in someinstances, can remain substantially unchanged.

The media source 1102 can be rotatable about an axis substantiallyparallel to the surface of the build plate 1104 in a direction R tocreate a shear force to separate one or more cured discrete portions ofa layer of a resin 1114 from the media source 1102. Thus, for example,as a discrete portion of the layer of the resin 1114 is cured, the mediasource 1102 can be rotated (e.g., by a predetermined amount) to separatethe cured discrete portion from the media source 1102. In addition tothe rotational motion of the media source 1102 in the direction R, oneor both of the media source 1102 can and the build plate 1104 can bemovable relative to the other one of the media source 1102 and the buildplate 1104 in a direction D substantially parallel to a surface 1108 ofthe build plate 1104. In general, the components of rotational andtranslational relative movement between the media source 1102 and thesurface 1108 of the build plate 1104 can be controlled to achieve adirection and speed of movement useful for curing and separatingdiscrete segments of the resin 1114 to form a given layer of athree-dimensional object. Further or instead, the build plate 1104 canbe movable in a direction perpendicular to the surface 1108 of the buildplate 1104. For example, the build plate 1104 can move in the directionperpendicular to the surface 1108 of the build plate 1104 followingformation of a given layer (e.g., to make space for a new layer to bebuilt upon the given layer).

In certain implementations, the media source 1102 can include asubstantially cylindrical tube transparent to light from the activationlight source 1106. For example, the substantially cylindrical tube canhave a longitudinal dimensional substantially parallel to the surface ofthe build plate, and the substantially cylindrical tube can be rotatableabout the longitudinal dimension to move the media source 1102 relativeto the substrate upon which a given layer is being formed. Thelongitudinal dimension of the substantially cylindrical tube can span adimension of the surface of the build plate 1104.

In some implementations, the media source 1102 can be disposed about theactivation light source 1106. Such a position of the media source 1102about the activation light source 1106 can facilitate, for example,isolating (e.g., thermally isolating) the activation light source 1106from other components of the fabrication system 1100. For example, ininstances in which the media source 1102 is a substantially cylindricaltube, the activation light source 1106 can be disposed in an interiorportion of the tube, where the activation light source 1106 can beprotected from heat and debris, among other things.

In some instances, the fabrication system 1100 can further include areservoir 1112. The media source 1102 can be, for example, partiallydisposed in the reservoir 1112, with rotation of the media source 1102moving a surface of the media source 1102 in the direction R from thereservoir 1112 toward the surface 1108 of the build plate 1104.Continuing with this example, as the media source 1102 rotates in thedirection R from the reservoir 1112 toward the surface 1108 of the buildplate 1104, the media source 1102 can deliver the resin 1114 to aposition between the activation light source 1106 and the surface 1108of the build plate 1104, where light energy from the activation lightsource 1106 can cure a discrete portion of a layer of the resin. Inaddition to delivering resin toward the build plate 1104, rotation ofthe media source 1102 in the direction R can return unused resin 1114′to the reservoir 1112.

The reservoir 1112 can include, for example, at least one mixer 1116disposed in the reservoir 1112. The at least one mixer 1116 can includea plurality of blades 1118 rotatable or otherwise movable in thereservoir 1112 to agitate the resin in the reservoir 1112. Suchagitation can, for example, reduce the likelihood that particles in theresin will settle in the reservoir 1112. Further, or instead, thefabrication system 1100 can include a heater 1120 in thermalcommunication with the reservoir 1112. In certain instances, heat fromthe heater 1120 can facilitate mixing of the resin 1114 by the at leastone mixer 1116.

FIG. 12 is a flow chart of an exemplary method 1200 of fabricating athree-dimensional object using a rotatable media source. By way ofexample, the exemplary method 1200 can be implemented ascomputer-readable instructions stored on the computer-readable storagemedium 122 (FIG. 1) and executable by the controller 120 (FIG. 1) tooperate the stereolithography system 100 (FIG. 1) including thefabrication system 1100 (FIG. 11).

As shown in step 1202, the exemplary method 1200 can include providing aresin to a media source disposed within a working volume defined by abuild chamber. The resin can be, for example, any one or more of theresins described herein. Providing the resin to the media source caninclude, for example, storing the resin in a reservoir with at least aportion of the media source in contact with the resin in the reservoir.

As shown in step 1204, the exemplary method 1200 can include curingdiscrete portions of a layer of the resin on a substrate carried on asurface of a build plate in the working volume. For example, curingdiscrete portions of the layer of the resin on the substrate can includedirecting light energy through the media source and at the discreteportions of the layer on the substrate. In certain instances, directinglight energy at the discrete portions of the layer on the substrate caninclude pausing rotation of the media source as light energy is directedat each discrete portion of the layer.

As shown in step 1206, the exemplary method 1200 can include rotatingthe media source about an axis substantially parallel to the surface ofthe build plate. The rotation of the media source can, for example,separate at least one of the cured discrete portions from the mediasource. As the media source is rotated about the axis substantiallyparallel to the surface of the build plate, at least a portion of themedia source can move through the reservoir containing the resin. Inparticular, the media source can move through the resin such that resincan be deposited on the media source and rotation of the media sourcedraws resin out of the reservoir to a position between the activationlight source and the surface of the build plate. The resin in thereservoir can be mixed, heated, or both according to any one or more ofthe methods described herein.

Other types of movement of the media source relative to the surface ofthe surface of the build plate are additionally, or alternatively,possible. For example, one or both of the build plate and the mediasource can be moved relative to one another to change a position of themedia source relative to the surface of the build plate in a directionsubstantially parallel to the surface of the build plate.

As shown in step 1208, the exemplary method 1200 can include, for eachlayer of a plurality of layers, repeating the steps of providing theresin to the media source, curing discrete portions of each given layer,and separating cured discrete portions of the each given layer to form athree-dimensional object.

In some instances, as shown in step 1210, the exemplary method 1200 caninclude moving the build plate (e.g., in a direction away from the mediasource) before building a subsequent layer of the three-dimensionalobject being formed.

While resins have been described as including particles suspended in oneor more binders, other configurations are additionally or alternativelypossible. For example, as described in greater detail below, resins caninclude particles that are substantially transparent to light of certainwavelengths. In general, substantial transparency of particles in aresin can facilitate achieving suitable penetration of light through alayer of the resin and, in turn, can be useful for forming bonds betweena layer being formed and an immediately preceding layer to form athree-dimensional object. Stated differently, substantial transparencyof the particles in the resin can usefully overcome disparate challengesassociated with achieving suitable light penetration in a layer of aresin to achieve sufficient intralayer bonding while the resin itselfincludes a high particle loading useful for forming a dense part.

Referring now to FIG. 13, a resin 1302 can include particles of a firstmaterial 1304, particles of a second material 1306, and a binder system1308 in which the particles of the first material 1304 and the particlesof the second material 1306 are suspended (e.g. substantiallyhomogeneously suspended). The particles of the second material 1306 canbe different from the particles of the first material 1304. For example,particles of the first material 1304 can be substantially transparent tolight of a wavelength sufficient to crosslink, polymerize, or both atleast one portion of the binder system (e.g., light having a wavelengthof about 300 nm to about 450 nm). Additionally, or alternatively, theparticles of the second material 1306 can include a metal or a materialotherwise substantially opaque to light of the wavelength sufficient tocrosslink, polymerize, or both, the at least one portion of the bindersystem 1308. Thus, it should be appreciated that, in a resin having ahigh loading of particles, the substantial transparency of the particlesof the first material 1304 to light of the wavelength sufficient tocrosslink and/or polymerize at least one portion of the binder system1308 can provide a pathway for the penetration of light to a suitabledepth within a layer of a three-dimensional object being formed.

In certain instances, the particles of the second material 1306 can havean average size less than the wavelength of the light sufficient tocrosslink, polymerize, or both, the at least one portion of the bindersystem 1308. Thus, in implementations, in which the particles of thesecond material 1306 are substantially opaque, the particles of thesecond material 1306 can be sized to be less likely to interfere withpenetration of light into the resin 1302.

The particles of the first material 1304 can include, for example, aceramic. In some implementations, the ceramic can be heated or otherwisechemically converted to form a metal suitable for formation of thethree-dimensional object. In certain instances, at least one portion ofthe binder system 1308 can be crosslinkable, polymerizable, or both,through exposure to light of a wavelength below a band gap of theceramic. As an example, the ceramic can include a metal oxide, such asany one or more of iron oxide, silicon oxide, aluminum oxide, zirconiumoxide, and chromium oxide. Additionally, or alternatively, the ceramiccan include a metal nitride, such as any one or more respective metalsselected from group VII or group VIII elements. Further or instead, theceramic can include a metal carbide (e.g., silicon carbide).

In certain instances, the particles of the first material 1304 caninclude one or more of an intermetallic and a ternary oxide.

The particles of the first material 1304 can be, in certainapplications, chemically convertible to a third material. Thus, forexample, an appropriate first material for certain applications caninclude selecting a material that is optically transparent to awavelength suitable for cross-linking and/or polymerizing at least aportion of a binder system 1308 while also being chemically convertible(e.g., through subsequent processing) to a third material useful forfabrication of the three-dimensional object. As a specific example, thefirst material can be selected such that the third material issubstantially the same composition as the second material. As a morespecific example, the second material can include copper, and the firstmaterial can be copper sulfide. Additionally, or alternatively, thefirst material can be selected for being chemically convertible to agiven third material through a desired process, such as a typicalpost-process performed on the three-dimensional object formed throughlayer-by-layer deposition of the resin 1302 according to any one or moreof the stereolithography methods described herein. By way of example,the first material can be selected as being chemically convertible tothe third material via thermally-activated decomposition or reduction.Thus, in the case in which the third material is substantially the samecomposition as the second material, the first material can be selectedas being chemically convertible to the second material viathermally-activated decomposition or reduction. Further, or instead, thefirst material can be a metal oxide reduceable to form a metal. Asdescribed in greater detail below, the first material can be a materialthat is chemically convertible to a material that can be alloyed withthe second material in instances in which the second material includes ametal.

The volumetric ratio of the particles of the first material 1304 to theparticles of the second material 1306 can be a function ofconsiderations related to achieving suitable penetration of light whilealso producing an acceptable amount of shrinkage in a three-dimensionalobject as the first material is converted to the third material. Forexample, the particles of the second material 1306 can be greater thanabout 10 percent by volume and less than about 30 percent by volume ofthe resin 1302. Additionally, or alternatively, the particles of thefirst material 1304 can be greater than about 20 percent and less thanabout 40 percent by volume of the resin 1302.

The binder system 1308 can include a first binder and a second binder.The first binder and the second binder can include combinations of anyone or more of the first binder and the second binder described herein.Thus, as an example, the first binder can be substantially non-reactiveunder exposure to the wavelength of light sufficient to crosslink orpolymerize the second binder and, additionally or alternatively, thefirst binder can be useful for facilitating spreading the resin 1302 aspart of a fabrication process.

FIG. 14 is a flow chart of an exemplary method 1400 of additivemanufacturing of a three-dimensional object using a resin includingparticles substantially transparent to light energy and suspended in abinder system. Unless otherwise indicated or made clear from thecontext, it should be appreciated that the exemplary method 1400 can becarried out using any one or more of the devices and systems of thepresent disclosure.

As shown in step 1402, the exemplary method 1400 can include providing aresin to a media source. The resin can include particles of a firstmaterial, particles of a second material, and a binder system in whichthe particles of the first material and the second material aresuspended and, thus, more specifically, can be the resin 1300 in FIG.13.

As shown in step 1404, the exemplary method 1400 can include directinglight energy in a predetermined pattern onto a layer of the resin on themedia source. The light energy can modify the resin, such as bycross-linking, polymerizing, or both, at least one portion of the bindersystem. Further, or instead, the particles of the first material can besubstantially transparent to the light energy, and the light energy cansubstantially penetrate the layer (e.g., penetrate the entire thicknessof the layer) to bind a given layer of the resin to an adjacent layer aspart of a fabrication process of the three-dimensional object.

As shown in step 1408, the exemplary method 1400 can include, for eachlayer of a plurality of layers, repeating the steps of providing resinto the media source, and directing light energy in a predeterminedpattern onto a given layer of the resin on the media source to form athree-dimensional object.

While resins have been described as including particles of a firstmaterial and particles of a second material to facilitate penetration oflight into a layer formed by the resin, it should be appreciated thatthe first material and the second material can additionally, oralternatively, be selected to form a desired alloy in the finishedthree-dimensional object.

Referring again to FIG. 13, the particles of the first material 1304 caninclude, for example, one or more of a ceramic, an intermetallic, orother material substantially transparent to light of a wavelengthsufficient to crosslink, polymerize, or both, at least one portion ofthe binder system 1308. The particles of the first material 1304 can bechemically convertible to a first metal (e.g., via reduction of a metaloxide), and the particles of the second material 1306 can include asecond metal alloyable with the first metal. Thus, in use, the particlesof the first material 1304 can be penetrated by light to bind a givenlayer to an adjacent layer and, once a three-dimensional object isformed through a layer-by-layer stereolithography process, the particlesof the first material 1304 can be converted into a material alloyablewith the second metal. Further, while a first metal and a second metalare described, it should be appreciated that additional metals and/oradditives can be included in the resin as necessary to achieve a targetalloy formulation in a finished part. In certain instances, theparticles of the first material 1304 can be in a relative concentrationto the particles of the second material 1306 such that an alloyincluding the first metal and the second metal meets a predeterminedmaterial standard. For example, the alloy including the first metal andthe second metal can meet an AISI material standard or other similarindustry standard.

In certain implementations, the first metal and the second metal can bealloyable into a stainless steel. For example, the first material can bean iron-based ceramic and the second material can be one or more ofchromium nickel, or alloys thereof. Examples of the iron-based ceramicinclude one or more of iron oxide and iron nitride.

The selection of an appropriate first material and an appropriate secondmaterial can be based on chemical stability. That is, because the firstmaterial undergoes chemical conversion to alloy with the secondmaterial, it is generally desirable to select the first material as thematerial that is more readily converted. Thus, for example, an oxide ofthe first metal can be less chemically stable than oxide of the secondmetal.

In certain implementations, particles of the first material can includea ternary oxide.

FIG. 15 is a flow chart of an exemplary method of additive manufacturingof a three-dimensional object by forming an alloy from particlessuspended in a resin. Unless otherwise indicated or made clear from thecontext, it should be appreciated that the exemplary method 1500 can becarried out using any one or more of the devices and systems of thepresent disclosure.

As shown in step 1502, the exemplary method 1500 can include providing alayer of a resin on a media source. The resin can be any one or more ofthe resins described herein and including particles of a first material,particles of a second material, and a binder system and, morespecifically, with the first material substantially transparent to lightof a wavelength sufficient to cross-link or polymerize at least aportion of a binder system in which the particles are suspended, and thefirst material chemically convertible into a first metal alloyable witha second metal of the second material.

As shown in step 1504, the exemplary method 1500 can include directinglight energy in a predetermined pattern onto the layer of the resin tocure the resin on a substrate carried by a build plate.

As shown in step 1508, the exemplary method 1500 can include, for eachlayer of a plurality of layers, repeating the steps of providing theresin, and directing light energy in a predetermined pattern onto agiven layer of the resin. Unless otherwise indicated, or made clear fromthe context the steps 1504 and 1508 should be understood to be analogousto the corresponding steps 1404 and 1408 described with respect to theexemplary method 1400 (FIG. 14).

As shown in step 1510, the exemplary method 1500 can include forming analloy including the first metal and the second metal. The alloy can be,for example, an alloy meeting a predetermined standard, such as one ormore industry standards for a given type of alloy. As an alternative oradditional example, the alloy can be a stainless steel.

Forming the alloy including the first metal and the second metal caninclude thermally processing the three-dimensional object. In certainimplementations, the first material can be chemically converted to thefirst metal by sintering the three-dimensional object at a sinteringtemperature. Additionally, or alternatively, forming the alloy includingthe first metal and the second metal can include infiltrating (e.g.,through wicking) the three-dimensional object with a liquid metal. Theliquid metal can be, for example, a component of the alloy including thefirst metal and the second metal. Further, or instead, the liquid metalcan include a third metal having a composition different from at leastone of the first metal and the second metal.

In some instances, the exemplary method 1500 can, further or instead,include debinding the binder system from the three-dimensional object.By way of example, such debinding can include any one or more of thedebinding processes described herein.

While the first material and the second material have been described asbeing metal or convertible into a metal, it should be appreciated thatat least one of the first material and the second material can be anadditive useful for forming an alloy. Further, or instead, it should beappreciated that the first material and the second material are recitedfor the sake of clarity of explanation and, more generally, the resincan include two or more materials processable (e.g., thermallyprocessable) into an alloy.

While resins have been described as including particles of differentcompositions to facilitate formation of strong three-dimensional objectsusing stereolithographic processes, other resins are additionally oralternatively possible. For example, resins can include one or morephotopolymers that can be usefully chemically converted to providesupport for a three-dimensional object formed through astereolithographic process as the three-dimensional object is thermallyprocessed to densify and, ultimately, form a finished part.

As an example, a resin can include particles of metal (e.g., iron) and abinder system in which the particles are suspended. The binder systemcan include a photopolymer crosslinkable or polymerizable upon exposureto light of a predetermined wavelength. Additionally, or alternatively,the photopolymer can be thermally decomposable to a first ceramicdissolvable in the metal or an alloy of the metal at a sinteringtemperature of the particles of the metal. Thus, in this way, theceramic can provide sintering support for strengthening thethree-dimensional part without being present in significant quantitiesin the three-dimensional part after sintering.

The photopolymer can be, for example, a silicone polymer and the firstceramic can be silicon carbide. In certain implementations, the bindersystem can include a second component containing carbon. The secondcomponent can be chemically convertible such that the silicon carbide isformed from the carbon on of the second component.

In certain instances, the particles of the metal can have an averagesize less than the wavelength of the light sufficient to crosslink orpolymerize the photopolymer. Such size can reduce the likelihood thatthe particles of the metal will interfere with penetration of the lightin a layer of the resin.

The molecular weight of the photopolymer can be increasable from lessthan about 1000 g/mol to greater than about 1000 g/mol under exposure tothe wavelength of light sufficient to crosslink or polymerize thephotopolymer.

In general, the particles of metal suspended in the binder system canhave a timescale of settling substantially greater than the duration oftime sufficient for the photopolymer to undergo crosslinking orpolymerization upon exposure to light of the predetermined wavelength.

FIG. 16 is a flow chart of an exemplary method 1600 of additivemanufacturing of a three-dimensional object using a resin including asilicone polymer. Unless otherwise indicated or made clear from thecontext, it should be appreciated that the exemplary method 1600 can becarried out using any one or more of the devices and systems of thepresent disclosure.

As shown in step 1602, the exemplary method 1600 can include providing aresin to a media source. The resin can include a silicone polymer and,further or instead, particles of metal suspended in the siliconepolymer. As shown in step 1604, the exemplary method 1600 can includedirecting light energy in a predetermined pattern in onto a layer of theresin on substrate carried by a build plate. The light energy cancrosslink or polymerize the silicone polymer. Unless otherwise indicatedor made clear from the context, it should be understood that steps 1602and 1604 of the exemplary method 1600 are analogous to the correspondingsteps 1402 and 1404 of the exemplary method 1400 (FIG. 14).

As shown in step 1608, the exemplary method 1600 can include, for eachlayer of a plurality of layers, repeating the steps of providing theresin and directing light energy in a predetermine pattern onto a givenlayer of a resin to form a three-dimensional object.

As shown in step 1610, the exemplary method 1600 can include thermallydecomposing the crosslinked or polymerized silicone polymer into aceramic. In implementations in which the resin includes particles ofmetal suspended in the silicone polymer, the exemplary method 1600 caninclude thermally processing (e.g., sintering) particles of metal in thethree-dimensional object containing the ceramic. The ceramic can, forexample, dissolve in the metal or an alloy of the metal as the particlesof the metal are thermally processed. For example, the ceramic materialcan include silicon carbide and the alloy of the metal can includesteel. Additionally, or alternatively, the exemplary method 1600 caninclude infiltrating a liquid metal into the ceramic material in thethree-dimensional object. The ceramic material in the metal can bedissolved in the liquid metal or in an alloy of the metal of the liquidmetal.

While resins have been described as including particles of differentmaterials to facilitate light penetration through a layer of the resin,other configurations are additionally or alternatively possible. Forexample, referring now to FIGS. 17, a resin 1700 can include particlesof a metal 1702 and a coating 1704 disposed on the particles of themetal 1702. The coating 1704 can be formed of a material different fromthe particles of the metal 1702, and the coating 1704 can have anaverage thickness of greater than about 3 percent and less than about 85percent of an average diameter of the particles of the metal. It shouldbe appreciated that a coating thickness in this range is substantiallylarger than natural oxide coatings that form on metals.

The particles of the metal 1702 and the coating 1704 can be suspended ina binder system 1706, which can include any one or more of the bindersdescribed herein. The material of the coating 1704 can be substantiallytransparent to light of a wavelength sufficient to crosslink,polymerize, or both, at least one portion of the binder system 1706(e.g., a wavelength of about 300 nm to about 450 nm). Thus, it should befurther understood that the coating 1704 can facilitate penetration oflight through a layer of the resin including coated metal particles. Anexemplary light path 1708 is shown passing through the resin 1700.

In general, the particles of the metal 1702 can be any of the variousdifferent metals described herein. Thus, for example, the particles ofthe metal 1702 can have an average size less than the wavelength of thelight sufficient to crosslink, polymerize, or both, the at least oneportion of the binder system 1706.

The material of the coating 1704 can include, for example, a ceramic. Insuch instances, the at least one portion of the binder system 1706 canbe crosslinkable, polymerizable, or both, through exposure to light of awavelength below a band gap of the ceramic. Further, or instead, theceramic can include a metal oxide, which can include one or more of ironoxide, silicon oxide, aluminum oxide, zirconium oxide, and chromiumoxide. Additionally, or alternatively, the ceramic can include a metalnitride, such as one or more nitrides of one or more respective metalsselected from the group VII or group VIII elements. Still further inaddition or further in the alternative, the ceramic can include a metalcarbide (e.g., silicon carbide).

In general, the material of the coating 1704 can include any of thetransparent materials described herein. Thus, for example, the materialof the coating 1704 can include an intermetallic, a ternary oxide, orboth. Further, or instead, the material of the coating 1704 can bechemically convertible to a metal (e.g., the metal of the particles). Incertain implementations, the material of the coating 1704 can include ametal oxide, and the material of the coating 1704 can be chemicallyreducible to a metal (e.g., the metal of the particles or a component ofan alloy).

While various different methods of providing a resin to a media sourcehave been described, it should be appreciated the use of other thincoating techniques is additionally or alternatively possible. Forexample, known thin coating techniques such as one or more of slot die,tape casting, silk screen, and the like can be used to deposit thinlayers of any one or more of the resins described herein onto asubstrate as part of a fabrication process of a three-dimensionalobject.

While three-dimensional objects described herein have been described asbeing formed from a single resin, it should be appreciated that thedevices, systems, and methods of the present disclosure have beendescribed in this way sake of clarity and efficiency of explanation and,unless otherwise specified, any one or more of the devices, systems, andmethods described herein can operate using more than one resin. Thus,more specifically, a plurality of resins can be combined on-demand toimpart desired variations in aesthetic and/or physicochemical propertiesin a three-dimensional object being formed. That is, the plurality ofresins can be combined to impart layer-by-layer variations along thethree-dimensional object and, additionally or alternatively, can becombined to impart intralayer variations along the three-dimensionalobject. For example, in instances in which different colors aredesirable in a finished part, resins with particles of different colors(e.g., red, green, and blue) can be combined on demand for a given layeror a given portion of a layer of the three-dimensional object forhigh-resolution control over the color of a finished part formed fromthe three-dimensional object. As an additional or alternative example,in instances in which different physicochemical properties are desirablein a finished part, a plurality of resins with different types ofparticles can be combined on-demand such that the aggregate combinationof the plurality of resins includes a distribution of particlesthermally processable to form the target variation in physicochemicalproperties along a finished part formed from the three-dimensionalobject.

In certain implementations, a resin can be provided on demand tofacilitate formation of an interface layer between one or more supportstructures and the three-dimensional object being formed. The interfacelayer can inhibit bonding of one or more support structures to thethree-dimensional object during thermal processing and/or debinding,thus facilitating removal of the one or more support structures duringfabrication of a finished part. That is, support structures can beusefully incorporated into the three-dimensional object to reduce thelikelihood of unintended sagging or other distortion associated withcertain structural features. However, in instances in which such supportstructures are not intended to form a portion of the finished part, oneor more resins can be selectively provided in all or a portion of agiven layer to form the interface layer.

The one or more resins can include one or more components useful forinhibiting bonding of the one or more support structures to thethree-dimensional object and, in general, the one or more components caninhibit bonding by imparting locally certain physicochemical propertiesto the interface layer. For example, material in the one or more of theresins forming the interface layer can be dissolvable for removal with asolvent prior to sintering the three-dimensional object. Additionally,or alternatively, material in the one or more resins forming theinterface layer can have a shrinkage rate differing from a shrinkagerate of one or more resins forming the three-dimensional object awayfrom the interface layer, with the difference in shrinkage ratesfacilitating separation of the interface layer from thethree-dimensional object during sintering and/or debinding. As still afurther or alternative example, the particles in the one or more resinsforming the interface layer can include a ceramic material while one ormore resins forming the three-dimensional object away from the interfacelayer can include metal. The ceramic material in the interface layer canshrink less than the metal in the three-dimensional object duringthermal processing.

The above systems, devices, methods, processes, and the like may berealized in hardware, software, or any combination of these suitable fora particular application. The hardware may include a general-purposecomputer and/or dedicated computing device. This includes realization inone or more microprocessors, microcontrollers, embeddedmicrocontrollers, programmable digital signal processors or otherprogrammable devices or processing circuitry, along with internal and/orexternal memory. This may also, or instead, include one or moreapplication specific integrated circuits, programmable gate arrays,programmable array logic components, or any other device or devices thatmay be configured to process electronic signals. It will further beappreciated that a realization of the processes or devices describedabove may include computer-executable code created using a structuredprogramming language such as C, an object oriented programming languagesuch as C++, or any other high-level or low-level programming language(including assembly languages, hardware description languages, anddatabase programming languages and technologies) that may be stored,compiled or interpreted to run on one of the above devices, as well asheterogeneous combinations of processors, processor architectures, orcombinations of different hardware and software. In another aspect, themethods may be embodied in systems that perform the steps thereof, andmay be distributed across devices in a number of ways. At the same time,processing may be distributed across devices such as the various systemsdescribed above, or all of the functionality may be integrated into adedicated, standalone device or other hardware. In another aspect, meansfor performing the steps associated with the processes described abovemay include any of the hardware and/or software described above. Allsuch permutations and combinations are intended to fall within the scopeof the present disclosure.

Embodiments disclosed herein may include computer program productscomprising computer-executable code or computer-usable code that, whenexecuting on one or more computing devices, performs any and/or all ofthe steps thereof. The code may be stored in a non-transitory fashion ina computer memory, which may be a memory from which the program executes(such as random access memory associated with a processor), or a storagedevice such as a disk drive, flash memory or any other optical,electromagnetic, magnetic, infrared or other device or combination ofdevices. In another aspect, any of the systems and methods describedabove may be embodied in any suitable transmission or propagation mediumcarrying computer-executable code and/or any inputs or outputs fromsame.

The method steps of the implementations described herein are intended toinclude any suitable method of causing such method steps to beperformed, consistent with the patentability of the following claims,unless a different meaning is expressly provided or otherwise clear fromthe context. So, for example performing the step of X includes anysuitable method for causing another party such as a remote user, aremote processing resource (e.g., a server or cloud computer) or amachine to perform the step of X. Similarly, performing steps X, Y and Zmay include any method of directing or controlling any combination ofsuch other individuals or resources to perform steps X, Y and Z toobtain the benefit of such steps. Thus, method steps of theimplementations described herein are intended to include any suitablemethod of causing one or more other parties or entities to perform thesteps, consistent with the patentability of the following claims, unlessa different meaning is expressly provided or otherwise clear from thecontext. Such parties or entities need not be under the direction orcontrol of any other party or entity, and need not be located within aparticular jurisdiction.

It should further be appreciated that the methods above are provided byway of example. Absent an explicit indication to the contrary, thedisclosed steps may be modified, supplemented, omitted, and/orre-ordered without departing from the scope of this disclosure.

It will be appreciated that the methods and systems described above areset forth by way of example and not of limitation. Numerous variations,additions, omissions, and other modifications will be apparent to one ofordinary skill in the art. In addition, the order or presentation ofmethod steps in the description and drawings above is not intended torequire this order of performing the recited steps unless a particularorder is expressly required or otherwise clear from the context. Thus,while particular embodiments have been shown and described, it will beapparent to those skilled in the art that various changes andmodifications in form and details may be made therein without departingfrom the spirit and scope of this disclosure and are intended to form apart of the invention as defined by the following claims, which are tobe interpreted in the broadest sense allowable by law.

What is claimed is:
 1. A resin comprising: particles of a firstmaterial; particles of a second material, the second material differentfrom the first material; and a binder system in which the particles ofthe first material and the particles of the second material aresuspended, the particles of the first material substantially transparentto light of a wavelength sufficient to crosslink, polymerize, or both,at least one component of the binder system.
 2. The resin of claim 1,wherein the particles of the first material and the particles of thesecond material are substantially homogeneously suspended in the bindersystem.
 3. The resin of claim 1, wherein the particles of the secondmaterial are substantially opaque to light of the wavelength sufficientto crosslink, polymerize, or both, the at least one component of thebinder system.
 4. The resin of claim 1, wherein the particles of thesecond material have an average size less than the wavelength of thelight sufficient to crosslink, polymerize, or both, the at least onecomponent of the binder system.
 5. The resin of claim 1, wherein theparticles of the first material include a ceramic.
 6. The resin of claim1, wherein the particles of the second material include a metal.
 7. Theresin of claim 1, wherein the first material is chemically convertibleto the second material.
 8. The resin of claim 7, wherein the firstmaterial is chemically convertible to the second material viathermally-activated decomposition or reduction.
 9. The resin of claim 1,wherein the first material is a metal oxide reduceable to form a metal.10. The resin of claim 1, wherein the first material includes a ceramic,an intermetallic, or both, and the particles of the first material arechemically convertible to a first metal, and the particles of a secondmaterial include a second metal alloyable with the first metal.
 11. Theresin of claim 10, wherein the particles of the first material are in arelative concentration to the particles of the second material such thatan alloy of the first metal and the second metal meets a predeterminedmaterial standard.
 12. The resin of claim 10, wherein an oxide of thefirst metal is less chemically stable than an oxide of the second metal.13. The resin of claim 1, wherein the binder system includes a firstbinder and a second binder, the first binder different from the secondbinder and in a mixture with the first binder, and the first bindersubstantially non-reactive under exposure to the wavelength of lightsufficient to crosslink or polymerize the second binder.
 14. The resinof claim 13, wherein the first binder is extractable from the secondbinder following exposure of the second binder to the wavelength oflight sufficient to crosslink or polymerize the second binder.
 15. Amethod of additive manufacturing of a three-dimensional object, themethod comprising: providing a layer of a resin on a media source, theresin including particles of a first material, particles of a secondmaterial, the second material different from the first material, and abinder system in which the particles of the first material and theparticles of the second material are suspended; directing light energyin a predetermined pattern onto the layer to cure the resin on asubstrate carried by a build plate, the particles of the first materialsubstantially transparent to the light energy, and the light energycrosslinking, polymerizing, or both, at least one component of thebinder system; and for each layer of a plurality of layers, repeatingthe steps of providing each respective layer of the resin, and directinglight energy in a predetermined pattern onto each respective layer ofthe resin to form a three-dimensional object.
 16. The method of claim15, wherein the light energy directed onto each layer penetrates therespective layer to bond successive layers of the plurality of layers ofthe three-dimensional obj ect.
 17. The method of claim 15, furthercomprising sintering the three-dimensional object, the sinteringtransforming the particles of the first material to a metal or anadditive in a metallic alloy.
 18. The method of claim 15, furthercomprising removing the binder system from the three-dimensional objectthrough a plurality of debinding processes.
 19. The method of claim 15,further comprising infiltrating the three-dimensional object with aliquid metal.
 20. The method of claim 19, wherein infiltrating thethree-dimensional object with the liquid metal includes replacing thebinder system with the liquid metal.